class Sequel::Dataset

A dataset represents an SQL query. Datasets can be used to select, insert, update and delete records.

Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely (datasets never cache results):

my_posts = DB[:posts].where(author: 'david') # no records are retrieved
my_posts.all # records are retrieved
my_posts.all # records are retrieved again

Datasets are frozen and use a functional style where modification methods return modified copies of the the dataset. This allows you to reuse datasets:

posts = DB[:posts]
davids_posts = posts.where(author: 'david')
old_posts = posts.where{stamp < Date.today - 7}
davids_old_posts = davids_posts.where{stamp < Date.today - 7}

Datasets are Enumerable objects, so they can be manipulated using any of the Enumerable methods, such as map, inject, etc.

For more information, see the “Dataset Basics” guide.

Constants

OPTS
TRUE_FREEZE

Whether Dataset#freeze can actually freeze datasets. True only on ruby 2.4+, as it requires clone(freeze: false)

1 - Methods that return modified datasets

↑ top

Constants

COLUMN_CHANGE_OPTS

The dataset options that require the removal of cached columns if changed.

CONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. inner_join) that call join_table with the symbol, passing along the arguments and block from the method call.

EMPTY_ARRAY
EXTENSIONS

Hash of extension name symbols to callable objects to load the extension into the Dataset object (usually by extending it with a module defined in the extension).

JOIN_METHODS

All methods that return modified datasets with a joined table added.

NON_SQL_OPTIONS

Which options don't affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.

QUERY_METHODS

Methods that return modified datasets

SIMPLE_SELECT_ALL_ALLOWED_FROM

From types allowed to be considered a simple_select_all

UNCONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. natural_join). They accept a table argument and options hash which is passed to join_table, and they raise an error if called with a block.

Public Class Methods

register_extension(ext, mod=nil, &block) click to toggle source

Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should either be a Module that the dataset is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.

If mod is a module, this also registers a Database extension that will extend all of the database's datasets.

   # File lib/sequel/dataset/query.rb
55 def self.register_extension(ext, mod=nil, &block)
56   if mod
57     raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block
58     if mod.is_a?(Module)
59       block = proc{|ds| ds.extend(mod)}
60       Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)}
61     else
62       block = mod
63     end
64   end
65   Sequel.synchronize{EXTENSIONS[ext] = block}
66 end

Public Instance Methods

_clone(opts = (return self; nil))

Save original clone implementation, as some other methods need to call it internally.

Alias for: clone
clone(opts = (return self; nil)) click to toggle source

Returns a new clone of the dataset with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted. This method should generally not be called directly by user code.

Calls superclass method
   # File lib/sequel/dataset/query.rb
84 def clone(opts = (return self; nil))
85   c = super(:freeze=>false)
86   c.opts.merge!(opts)
87   unless opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
88     c.clear_columns_cache
89   end
90   c.freeze
91 end
Also aliased as: _clone
distinct(*args, &block) click to toggle source

Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. If a block is given, it is treated as a virtual row block, similar to where. Raises an error if arguments are given and DISTINCT ON is not supported.

DB[:items].distinct # SQL: SELECT DISTINCT * FROM items
DB[:items].order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
DB[:items].order(:id).distinct{func(:id)} # SQL: SELECT DISTINCT ON (func(id)) * FROM items ORDER BY id

There is support for emualting the DISTINCT ON support in MySQL, but it does not support the ORDER of the dataset, and also doesn't work in many cases if the ONLY_FULL_GROUP_BY sql_mode is used, which is the default on MySQL 5.7.5+.

    # File lib/sequel/dataset/query.rb
121 def distinct(*args, &block)
122   virtual_row_columns(args, block)
123   if args.empty?
124     cached_dataset(:_distinct_ds){clone(:distinct => EMPTY_ARRAY)}
125   else
126     raise(InvalidOperation, "DISTINCT ON not supported") unless supports_distinct_on?
127     clone(:distinct => args.freeze)
128   end
129 end
except(dataset, opts=OPTS) click to toggle source

Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].except(DB[:other_items])
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1

DB[:items].except(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items EXCEPT ALL SELECT * FROM other_items

DB[:items].except(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
148 def except(dataset, opts=OPTS)
149   raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
150   raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
151   compound_clone(:except, dataset, opts)
152 end
exclude(*cond, &block) click to toggle source

Performs the inverse of Dataset#where. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

DB[:items].exclude(category: 'software', id: 3)
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

Also note that SQL uses 3-valued boolean logic (true, false, NULL), so the inverse of a true condition is a false condition, and will still not match rows that were NULL originally. If you take the earlier example:

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

Note that this does not match rows where category is NULL. This is because NULL is an unknown value, and you do not know whether or not the NULL category is software. You can explicitly specify how to handle NULL values if you want:

DB[:items].exclude(Sequel.~(category: nil) & {category: 'software'})
# SELECT * FROM items WHERE ((category IS NULL) OR (category != 'software'))
    # File lib/sequel/dataset/query.rb
178 def exclude(*cond, &block)
179   add_filter(:where, cond, true, &block)
180 end
exclude_having(*cond, &block) click to toggle source

Inverts the given conditions and adds them to the HAVING clause.

DB[:items].select_group(:name).exclude_having{count(name) < 2}
# SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
189 def exclude_having(*cond, &block)
190   add_filter(:having, cond, true, &block)
191 end
extension(*a) click to toggle source

Return a clone of the dataset loaded with the given dataset extensions. If no related extension file exists or the extension does not have specific support for Dataset objects, an Error will be raised.

    # File lib/sequel/dataset/query.rb
197 def extension(*a)
198   c = _clone(:freeze=>false)
199   c.send(:_extension!, a)
200   c.freeze
201 end
filter(*cond, &block) click to toggle source

Alias for where.

    # File lib/sequel/dataset/query.rb
213 def filter(*cond, &block)
214   where(*cond, &block)
215 end
for_update() click to toggle source

Returns a cloned dataset with a :update lock style.

DB[:table].for_update # SELECT * FROM table FOR UPDATE
    # File lib/sequel/dataset/query.rb
220 def for_update
221   cached_dataset(:_for_update_ds){lock_style(:update)}
222 end
from(*source, &block) click to toggle source

Returns a copy of the dataset with the source changed. If no source is given, removes all tables. If multiple sources are given, it is the same as using a CROSS JOIN (cartesian product) between all tables. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].from # SQL: SELECT *
DB[:items].from(:blah) # SQL: SELECT * FROM blah
DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo
DB[:items].from{fun(arg)} # SQL: SELECT * FROM fun(arg)
    # File lib/sequel/dataset/query.rb
233 def from(*source, &block)
234   virtual_row_columns(source, block)
235   table_alias_num = 0
236   ctes = nil
237   source.map! do |s|
238     case s
239     when Dataset
240       if hoist_cte?(s)
241         ctes ||= []
242         ctes += s.opts[:with]
243         s = s.clone(:with=>nil)
244       end
245       SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
246     when Symbol
247       sch, table, aliaz = split_symbol(s)
248       if aliaz
249         s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
250         SQL::AliasedExpression.new(s, aliaz.to_sym)
251       else
252         s
253       end
254     else
255       s
256     end
257   end
258   o = {:from=>source.empty? ? nil : source.freeze}
259   o[:with] = ((opts[:with] || EMPTY_ARRAY) + ctes).freeze if ctes
260   o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
261   clone(o)
262 end
from_self(opts=OPTS) click to toggle source

Returns a dataset selecting from the current dataset. Options:

:alias

Controls the alias of the table

:column_aliases

Also aliases columns, using derived column lists. Only used in conjunction with :alias.

ds = DB[:items].order(:name).select(:id, :name)
# SELECT id,name FROM items ORDER BY name

ds.from_self
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1

ds.from_self(alias: :foo)
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo

ds.from_self(alias: :foo, column_aliases: [:c1, :c2])
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo(c1, c2)
    # File lib/sequel/dataset/query.rb
281 def from_self(opts=OPTS)
282   fs = {}
283   @opts.keys.each{|k| fs[k] = nil unless non_sql_option?(k)}
284   pr = proc do
285     c = clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self)
286     if cols = _columns
287       c.send(:columns=, cols)
288     end
289     c
290   end
291 
292   cache ? cached_dataset(:_from_self_ds, &pr) : pr.call
293 end
grep(columns, patterns, opts=OPTS) click to toggle source

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions if the database supports that. Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.

Options (all are boolean):

:all_columns

All columns must be matched to any of the given patterns.

:all_patterns

All patterns must match at least one of the columns.

:case_insensitive

Use a case insensitive pattern match (the default is case sensitive if the database supports it).

If both :all_columns and :all_patterns are true, all columns must match all patterns.

Examples:

dataset.grep(:a, '%test%')
# SELECT * FROM items WHERE (a LIKE '%test%' ESCAPE '\')

dataset.grep([:a, :b], %w'%test% foo')
# SELECT * FROM items WHERE ((a LIKE '%test%' ESCAPE '\') OR (a LIKE 'foo' ESCAPE '\')
#   OR (b LIKE '%test%' ESCAPE '\') OR (b LIKE 'foo' ESCAPE '\'))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (b LIKE '%foo%' ESCAPE '\'))
#   AND ((a LIKE '%bar%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_columns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (a LIKE '%bar%' ESCAPE '\'))
#   AND ((b LIKE '%foo%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true, all_columns: true)
# SELECT * FROM a WHERE ((a LIKE '%foo%' ESCAPE '\') AND (b LIKE '%foo%' ESCAPE '\')
#   AND (a LIKE '%bar%' ESCAPE '\') AND (b LIKE '%bar%' ESCAPE '\'))
    # File lib/sequel/dataset/query.rb
330 def grep(columns, patterns, opts=OPTS)
331   if opts[:all_patterns]
332     conds = Array(patterns).map do |pat|
333       SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
334     end
335     where(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds))
336   else
337     conds = Array(columns).map do |c|
338       SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
339     end
340     where(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds))
341   end
342 end
group(*columns, &block) click to toggle source

Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].group(:id) # SELECT * FROM items GROUP BY id
DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name
DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
    # File lib/sequel/dataset/query.rb
351 def group(*columns, &block)
352   virtual_row_columns(columns, block)
353   clone(:group => (columns.compact.empty? ? nil : columns.freeze))
354 end
group_and_count(*columns, &block) click to toggle source

Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to where.

Examples:

DB[:items].group_and_count(:name).all
# SELECT name, count(*) AS count FROM items GROUP BY name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count(:first_name, :last_name).all
# SELECT first_name, last_name, count(*) AS count FROM items GROUP BY first_name, last_name
# => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]

DB[:items].group_and_count(Sequel[:first_name].as(:name)).all
# SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count{substr(:first_name, 1, 1).as(:initial)}.all
# SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1)
# => [{:initial=>'a', :count=>1}, ...]
    # File lib/sequel/dataset/query.rb
382 def group_and_count(*columns, &block)
383   select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT)
384 end
group_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the list of existing columns to group on. If no existing columns are present this method simply sets the columns as the initial ones to group on.

DB[:items].group_append(:b) # SELECT * FROM items GROUP BY b
DB[:items].group(:a).group_append(:b) # SELECT * FROM items GROUP BY a, b
    # File lib/sequel/dataset/query.rb
392 def group_append(*columns, &block)
393   columns = @opts[:group] + columns if @opts[:group]
394   group(*columns, &block)
395 end
group_by(*columns, &block) click to toggle source

Alias of group

    # File lib/sequel/dataset/query.rb
357 def group_by(*columns, &block)
358   group(*columns, &block)
359 end
group_cube() click to toggle source

Adds the appropriate CUBE syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
398 def group_cube
399   raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
400   clone(:group_options=>:cube)
401 end
group_rollup() click to toggle source

Adds the appropriate ROLLUP syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
404 def group_rollup
405   raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
406   clone(:group_options=>:rollup)
407 end
grouping_sets() click to toggle source

Adds the appropriate GROUPING SETS syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
410 def grouping_sets
411   raise Error, "GROUP BY GROUPING SETS not supported on #{db.database_type}" unless supports_grouping_sets?
412   clone(:group_options=>:"grouping sets")
413 end
having(*cond, &block) click to toggle source

Returns a copy of the dataset with the HAVING conditions changed. See where for argument types.

DB[:items].group(:sum).having(sum: 10)
# SELECT * FROM items GROUP BY sum HAVING (sum = 10)
    # File lib/sequel/dataset/query.rb
419 def having(*cond, &block)
420   add_filter(:having, cond, &block)
421 end
intersect(dataset, opts=OPTS) click to toggle source

Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].intersect(DB[:other_items])
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1

DB[:items].intersect(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items INTERSECT ALL SELECT * FROM other_items

DB[:items].intersect(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
440 def intersect(dataset, opts=OPTS)
441   raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
442   raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
443   compound_clone(:intersect, dataset, opts)
444 end
invert() click to toggle source

Inverts the current WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.

DB[:items].where(category: 'software').invert
# SELECT * FROM items WHERE (category != 'software')

DB[:items].where(category: 'software', id: 3).invert
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
457 def invert
458   cached_dataset(:_invert_ds) do
459     having, where = @opts.values_at(:having, :where)
460     if having.nil? && where.nil?
461       where(false)
462     else
463       o = {}
464       o[:having] = SQL::BooleanExpression.invert(having) if having
465       o[:where] = SQL::BooleanExpression.invert(where) if where
466       clone(o)
467     end
468   end
469 end
join(*args, &block) click to toggle source

Alias of inner_join

    # File lib/sequel/dataset/query.rb
472 def join(*args, &block)
473   inner_join(*args, &block)
474 end
join_table(type, table, expr=nil, options=OPTS) { |table_name, last_alias, opts || EMPTY_ARRAY| ... } click to toggle source

Returns a joined dataset. Not usually called directly, users should use the appropriate join method (e.g. join, left_join, natural_join, cross_join) which fills in the type argument.

Takes the following arguments:

type

The type of join to do (e.g. :inner)

table

table to join into the current dataset. Generally one of the following types:

String, Symbol

identifier used as table or view name

Dataset

a subselect is performed with an alias of tN for some value of N

SQL::Function

set returning function

SQL::AliasedExpression

already aliased expression. Uses given alias unless overridden by the :table_alias option.

expr

conditions used when joining, depends on type:

Hash, Array of pairs

Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.

Array

If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.

nil

If a block is not given, doesn't use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses an ON clause based on the block, see below.

otherwise

Treats the argument as a filter expression, so strings are considered literal, symbols specify boolean columns, and Sequel expressions can be used. Uses a JOIN with an ON clause.

options

a hash of options, with the following keys supported:

:table_alias

Override the table alias used when joining. In general you shouldn't use this option, you should provide the appropriate SQL::AliasedExpression as the table argument.

:implicit_qualifier

The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.

:reset_implicit_qualifier

Can set to false to ignore this join when future joins determine qualifier for implicit conditions.

:qualify

Can be set to false to not do any implicit qualification. Can be set to :deep to use the Qualifier AST Transformer, which will attempt to qualify subexpressions of the expression tree. Can be set to :symbol to only qualify symbols. Defaults to the value of default_join_table_qualification.

block

The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause. Unlike where, this block is not treated as a virtual row block.

Examples:

DB[:a].join_table(:cross, :b)
# SELECT * FROM a CROSS JOIN b

DB[:a].join_table(:inner, DB[:b], c: d)
# SELECT * FROM a INNER JOIN (SELECT * FROM b) AS t1 ON (t1.c = a.d)

DB[:a].join_table(:left, Sequel[:b].as(:c), [:d])
# SELECT * FROM a LEFT JOIN b AS c USING (d)

DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js|
  (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)}
end
# SELECT * FROM a NATURAL JOIN b INNER JOIN c
#   ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
    # File lib/sequel/dataset/query.rb
535 def join_table(type, table, expr=nil, options=OPTS, &block)
536   if hoist_cte?(table)
537     s, ds = hoist_cte(table)
538     return s.join_table(type, ds, expr, options, &block)
539   end
540 
541   using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
542   if using_join && !supports_join_using?
543     h = {}
544     expr.each{|e| h[e] = e}
545     return join_table(type, table, h, options)
546   end
547 
548   table_alias = options[:table_alias]
549 
550   if table.is_a?(SQL::AliasedExpression)
551     table_expr = if table_alias
552       SQL::AliasedExpression.new(table.expression, table_alias, table.columns)
553     else
554       table
555     end
556     table = table_expr.expression
557     table_name = table_alias = table_expr.alias
558   elsif table.is_a?(Dataset)
559     if table_alias.nil?
560       table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
561       table_alias = dataset_alias(table_alias_num)
562     end
563     table_name = table_alias
564     table_expr = SQL::AliasedExpression.new(table, table_alias)
565   else
566     table, implicit_table_alias = split_alias(table)
567     table_alias ||= implicit_table_alias
568     table_name = table_alias || table
569     table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table
570   end
571 
572   join = if expr.nil? and !block
573     SQL::JoinClause.new(type, table_expr)
574   elsif using_join
575     raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
576     SQL::JoinUsingClause.new(expr, type, table_expr)
577   else
578     last_alias = options[:implicit_qualifier] || @opts[:last_joined_table] || first_source_alias
579     qualify_type = options[:qualify]
580     if Sequel.condition_specifier?(expr)
581       expr = expr.map do |k, v|
582         qualify_type = default_join_table_qualification if qualify_type.nil?
583         case qualify_type
584         when false
585           nil # Do no qualification
586         when :deep
587           k = Sequel::Qualifier.new(table_name).transform(k)
588           v = Sequel::Qualifier.new(last_alias).transform(v)
589         else
590           k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
591           v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
592         end
593         [k,v]
594       end
595       expr = SQL::BooleanExpression.from_value_pairs(expr)
596     end
597     if block
598       expr2 = yield(table_name, last_alias, @opts[:join] || EMPTY_ARRAY)
599       expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
600     end
601     SQL::JoinOnClause.new(expr, type, table_expr)
602   end
603 
604   opts = {:join => ((@opts[:join] || EMPTY_ARRAY) + [join]).freeze}
605   opts[:last_joined_table] = table_name unless options[:reset_implicit_qualifier] == false
606   opts[:num_dataset_sources] = table_alias_num if table_alias_num
607   clone(opts)
608 end
lateral() click to toggle source

Marks this dataset as a lateral dataset. If used in another dataset's FROM or JOIN clauses, it will surround the subquery with LATERAL to enable it to deal with previous tables in the query:

DB.from(:a, DB[:b].where(Sequel[:a][:c]=>Sequel[:b][:d]).lateral)
# SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))
    # File lib/sequel/dataset/query.rb
629 def lateral
630   cached_dataset(:_lateral_ds){clone(:lateral=>true)}
631 end
limit(l, o = (no_offset = true; nil)) click to toggle source

If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.

DB[:items].limit(10) # SELECT * FROM items LIMIT 10
DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20
DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10
DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10
DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
    # File lib/sequel/dataset/query.rb
643 def limit(l, o = (no_offset = true; nil))
644   return from_self.limit(l, o) if @opts[:sql]
645 
646   if l.is_a?(Range)
647     no_offset = false
648     o = l.first
649     l = l.last - l.first + (l.exclude_end? ? 0 : 1)
650   end
651   l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
652   if l.is_a?(Integer)
653     raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
654   end
655 
656   ds = clone(:limit=>l)
657   ds = ds.offset(o) unless no_offset
658   ds
659 end
lock_style(style) click to toggle source

Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. You should never pass a string to this method that is derived from user input, as that can lead to SQL injection.

A symbol may be used for database independent locking behavior, but all supported symbols have separate methods (e.g. for_update).

DB[:items].lock_style('FOR SHARE NOWAIT')
# SELECT * FROM items FOR SHARE NOWAIT
DB[:items].lock_style('FOR UPDATE OF table1 SKIP LOCKED')
# SELECT * FROM items FOR UPDATE OF table1 SKIP LOCKED
    # File lib/sequel/dataset/query.rb
673 def lock_style(style)
674   clone(:lock => style)
675 end
naked() click to toggle source

Returns a cloned dataset without a row_proc.

ds = DB[:items].with_row_proc(:invert.to_proc)
ds.all # => [{2=>:id}]
ds.naked.all # => [{:id=>2}]
    # File lib/sequel/dataset/query.rb
682 def naked
683   cached_dataset(:_naked_ds){with_row_proc(nil)}
684 end
nowait() click to toggle source

Returns a copy of the dataset that will raise a DatabaseLockTimeout instead of waiting for rows that are locked by another transaction

DB[:items].for_update.nowait
# SELECT * FROM items FOR UPDATE NOWAIT
    # File lib/sequel/dataset/query.rb
691 def nowait
692   cached_dataset(:_nowait_ds) do
693     raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait?
694     clone(:nowait=>true)
695   end
696 end
offset(o) click to toggle source

Returns a copy of the dataset with a specified order. Can be safely combined with limit. If you call limit with an offset, it will override override the offset if you've called offset first.

DB[:items].offset(10) # SELECT * FROM items OFFSET 10
    # File lib/sequel/dataset/query.rb
703 def offset(o)
704   o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
705   if o.is_a?(Integer)
706     raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
707   end
708   clone(:offset => o)
709 end
or(*cond, &block) click to toggle source

Adds an alternate filter to an existing WHERE clause using OR. If there is no WHERE clause, then the default is WHERE true, and OR would be redundant, so return the dataset in that case.

DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b
DB[:items].or(:b) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
717 def or(*cond, &block)
718   if @opts[:where].nil?
719     self
720   else
721     add_filter(:where, cond, false, :OR, &block)
722   end
723 end
order(*columns, &block) click to toggle source

Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].order(:name) # SELECT * FROM items ORDER BY name
DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b
DB[:items].order(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b
DB[:items].order(Sequel[:a] + :b) # SELECT * FROM items ORDER BY (a + b)
DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC
DB[:items].order(Sequel.asc(:name, :nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
DB[:items].order(nil) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
739 def order(*columns, &block)
740   virtual_row_columns(columns, block)
741   clone(:order => (columns.compact.empty?) ? nil : columns.freeze)
742 end
order_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the end of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_append(:b) # SELECT * FROM items ORDER BY a, b
    # File lib/sequel/dataset/query.rb
749 def order_append(*columns, &block)
750   columns = @opts[:order] + columns if @opts[:order]
751   order(*columns, &block)
752 end
order_by(*columns, &block) click to toggle source

Alias of order

    # File lib/sequel/dataset/query.rb
755 def order_by(*columns, &block)
756   order(*columns, &block)
757 end
order_more(*columns, &block) click to toggle source

Alias of order_append.

    # File lib/sequel/dataset/query.rb
760 def order_more(*columns, &block)
761   order_append(*columns, &block)
762 end
order_prepend(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the beginning of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
    # File lib/sequel/dataset/query.rb
769 def order_prepend(*columns, &block)
770   ds = order(*columns, &block)
771   @opts[:order] ? ds.order_append(*@opts[:order]) : ds
772 end
qualify(table=(cache=true; first_source)) click to toggle source

Qualify to the given table, or first source if no table is given.

DB[:items].where(id: 1).qualify
# SELECT items.* FROM items WHERE (items.id = 1)

DB[:items].where(id: 1).qualify(:i)
# SELECT i.* FROM items WHERE (i.id = 1)
    # File lib/sequel/dataset/query.rb
781 def qualify(table=(cache=true; first_source))
782   o = @opts
783   return self if o[:sql]
784 
785   pr = proc do
786     h = {}
787     (o.keys & QUALIFY_KEYS).each do |k|
788       h[k] = qualified_expression(o[k], table)
789     end
790     h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty?
791     clone(h)
792   end
793 
794   cache ? cached_dataset(:_qualify_ds, &pr) : pr.call
795 end
returning(*values) click to toggle source

Modify the RETURNING clause, only supported on a few databases. If returning is used, instead of insert returning the autogenerated primary key or update/delete returning the number of modified rows, results are returned using fetch_rows.

DB[:items].returning # RETURNING *
DB[:items].returning(nil) # RETURNING NULL
DB[:items].returning(:id, :name) # RETURNING id, name

DB[:items].returning.insert(:a=>1) do |hash|
  # hash for each row inserted, with values for all columns
end
DB[:items].returning.update(:a=>1) do |hash|
  # hash for each row updated, with values for all columns
end
DB[:items].returning.delete(:a=>1) do |hash|
  # hash for each row deleted, with values for all columns
end
    # File lib/sequel/dataset/query.rb
815 def returning(*values)
816   if values.empty?
817     cached_dataset(:_returning_ds) do
818       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
819       clone(:returning=>EMPTY_ARRAY)
820     end
821   else
822     raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
823     clone(:returning=>values.freeze)
824   end
825 end
reverse(*order, &block) click to toggle source

Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.

DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC
DB[:items].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC
DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
    # File lib/sequel/dataset/query.rb
834 def reverse(*order, &block)
835   if order.empty? && !block
836     cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))}
837   else
838     virtual_row_columns(order, block)
839     order(*invert_order(order.empty? ? @opts[:order] : order.freeze))
840   end
841 end
reverse_order(*order, &block) click to toggle source

Alias of reverse

    # File lib/sequel/dataset/query.rb
844 def reverse_order(*order, &block)
845   reverse(*order, &block)
846 end
select(*columns, &block) click to toggle source

Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to where.

DB[:items].select(:a) # SELECT a FROM items
DB[:items].select(:a, :b) # SELECT a, b FROM items
DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
    # File lib/sequel/dataset/query.rb
855 def select(*columns, &block)
856   virtual_row_columns(columns, block)
857   clone(:select => columns.freeze)
858 end
select_all(*tables) click to toggle source

Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.

DB[:items].select(:a).select_all # SELECT * FROM items
DB[:items].select_all(:items) # SELECT items.* FROM items
DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
    # File lib/sequel/dataset/query.rb
867 def select_all(*tables)
868   if tables.empty?
869     cached_dataset(:_select_all_ds){clone(:select => nil)}
870   else
871     select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze)
872   end
873 end
select_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.

DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items
DB[:items].select_append(:b) # SELECT *, b FROM items
    # File lib/sequel/dataset/query.rb
882 def select_append(*columns, &block)
883   cur_sel = @opts[:select]
884   if !cur_sel || cur_sel.empty?
885     unless supports_select_all_and_column?
886       return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_append(*columns, &block)
887     end
888     cur_sel = [WILDCARD]
889   end
890   select(*(cur_sel + columns), &block)
891 end
select_group(*columns, &block) click to toggle source

Set both the select and group clauses with the given columns. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to where.

DB[:items].select_group(:a, :b)
# SELECT a, b FROM items GROUP BY a, b

DB[:items].select_group(Sequel[:c].as(:a)){f(c2)}
# SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
    # File lib/sequel/dataset/query.rb
902 def select_group(*columns, &block)
903   virtual_row_columns(columns, block)
904   select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
905 end
select_more(*columns, &block) click to toggle source

Alias for select_append.

    # File lib/sequel/dataset/query.rb
908 def select_more(*columns, &block)
909   select_append(*columns, &block)
910 end
server(servr) click to toggle source

Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.

DB[:items].all # Uses the :read_only or :default server
DB[:items].delete # Uses the :default server
DB[:items].server(:blah).delete # Uses the :blah server
    # File lib/sequel/dataset/query.rb
921 def server(servr)
922   clone(:server=>servr)
923 end
server?(server) click to toggle source

If the database uses sharding and the current dataset has not had a server set, return a cloned dataset that uses the given server. Otherwise, return the receiver directly instead of returning a clone.

    # File lib/sequel/dataset/query.rb
928 def server?(server)
929   if db.sharded? && !opts[:server]
930     server(server)
931   else
932     self
933   end
934 end
skip_limit_check() click to toggle source

Specify that the check for limits/offsets when updating/deleting be skipped for the dataset.

    # File lib/sequel/dataset/query.rb
937 def skip_limit_check
938   cached_dataset(:_skip_limit_check_ds) do
939     clone(:skip_limit_check=>true)
940   end
941 end
skip_locked() click to toggle source

Skip locked rows when returning results from this dataset.

    # File lib/sequel/dataset/query.rb
944 def skip_locked
945   cached_dataset(:_skip_locked_ds) do
946     raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked?
947     clone(:skip_locked=>true)
948   end
949 end
unfiltered() click to toggle source

Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).unfiltered
# SELECT * FROM items GROUP BY a
    # File lib/sequel/dataset/query.rb
955 def unfiltered
956   cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)}
957 end
ungrouped() click to toggle source

Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).ungrouped
# SELECT * FROM items WHERE b
    # File lib/sequel/dataset/query.rb
963 def ungrouped
964   cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)}
965 end
union(dataset, opts=OPTS) click to toggle source

Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use UNION ALL instead of UNION, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].union(DB[:other_items])
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1

DB[:items].union(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items UNION ALL SELECT * FROM other_items

DB[:items].union(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
983 def union(dataset, opts=OPTS)
984   compound_clone(:union, dataset, opts)
985 end
unlimited() click to toggle source

Returns a copy of the dataset with no limit or offset.

DB[:items].limit(10, 20).unlimited # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
990 def unlimited
991   cached_dataset(:_unlimited_ds){clone(:limit=>nil, :offset=>nil)}
992 end
unordered() click to toggle source

Returns a copy of the dataset with no order.

DB[:items].order(:a).unordered # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
997 def unordered
998   cached_dataset(:_unordered_ds){clone(:order=>nil)}
999 end
where(*cond, &block) click to toggle source

Returns a copy of the dataset with the given WHERE conditions imposed upon it.

Accepts the following argument types:

Hash, Array of pairs

list of equality/inclusion expressions

Symbol

taken as a boolean column argument (e.g. WHERE active)

Sequel::SQL::BooleanExpression, Sequel::LiteralString

an existing condition expression, probably created using the Sequel expression filter DSL.

where also accepts a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions. For more details on the virtual row support, see the “Virtual Rows” guide

If both a block and regular argument are provided, they get ANDed together.

Examples:

DB[:items].where(id: 3)
# SELECT * FROM items WHERE (id = 3)

DB[:items].where(Sequel.lit('price < ?', 100))
# SELECT * FROM items WHERE price < 100

DB[:items].where([[:id, [1,2,3]], [:id, 0..10]])
# SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))

DB[:items].where(Sequel.lit('price < 100'))
# SELECT * FROM items WHERE price < 100

DB[:items].where(:active)
# SELECT * FROM items WHERE :active

DB[:items].where{price < 100}
# SELECT * FROM items WHERE (price < 100)

Multiple where calls can be chained for scoping:

software = dataset.where(category: 'software').where{price < 100}
# SELECT * FROM items WHERE ((category = 'software') AND (price < 100))

See the “Dataset Filtering” guide for more examples and details.

     # File lib/sequel/dataset/query.rb
1043 def where(*cond, &block)
1044   add_filter(:where, cond, &block)
1045 end
with(name, dataset, opts=OPTS) click to toggle source

Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query. Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:recursive

Specify that this is a recursive CTE

DB[:items].with(:items, DB[:syx].where(Sequel[:name].like('A%')))
# WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%' ESCAPE '\')) SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1055 def with(name, dataset, opts=OPTS)
1056   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1057   if hoist_cte?(dataset)
1058     s, ds = hoist_cte(dataset)
1059     s.with(name, ds, opts)
1060   else
1061     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze)
1062   end
1063 end
with_extend(*mods, &block) click to toggle source

Return a clone of the dataset extended with the given modules. Note that like Object#extend, when multiple modules are provided as arguments the cloned dataset is extended with the modules in reverse order. If a block is provided, a DatasetModule is created using the block and the clone is extended with that module after any modules given as arguments.

     # File lib/sequel/dataset/query.rb
1100 def with_extend(*mods, &block)
1101   c = _clone(:freeze=>false)
1102   c.extend(*mods) unless mods.empty?
1103   c.extend(DatasetModule.new(&block)) if block
1104   c.freeze
1105 end
with_recursive(name, nonrecursive, recursive, opts=OPTS) click to toggle source

Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE. Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:union_all

Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts.

DB[:t].with_recursive(:t,
  DB[:i1].select(:id, :parent_id).where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select(Sequel[:i1][:id], Sequel[:i1][:parent_id]),
  :args=>[:id, :parent_id])

# WITH RECURSIVE t(id, parent_id) AS (
#   SELECT id, parent_id FROM i1 WHERE (parent_id IS NULL)
#   UNION ALL
#   SELECT i1.id, i1.parent_id FROM i1 INNER JOIN t ON (t.id = i1.parent_id)
# ) SELECT * FROM t
     # File lib/sequel/dataset/query.rb
1081 def with_recursive(name, nonrecursive, recursive, opts=OPTS)
1082   raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
1083   if hoist_cte?(nonrecursive)
1084     s, ds = hoist_cte(nonrecursive)
1085     s.with_recursive(name, ds, recursive, opts)
1086   elsif hoist_cte?(recursive)
1087     s, ds = hoist_cte(recursive)
1088     s.with_recursive(name, nonrecursive, ds, opts)
1089   else
1090     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]).freeze)
1091   end
1092 end
with_row_proc(callable) click to toggle source

Returns a cloned dataset with the given row_proc.

ds = DB[:items]
ds.all # => [{:id=>2}]
ds.with_row_proc(:invert.to_proc).all # => [{2=>:id}]
     # File lib/sequel/dataset/query.rb
1122 def with_row_proc(callable)
1123   clone(:row_proc=>callable)
1124 end
with_sql(sql, *args) click to toggle source

Returns a copy of the dataset with the static SQL used. This is useful if you want to keep the same row_proc/graph, but change the SQL used to custom SQL.

DB[:items].with_sql('SELECT * FROM foo') # SELECT * FROM foo

You can use placeholders in your SQL and provide arguments for those placeholders:

DB[:items].with_sql('SELECT ? FROM foo', 1) # SELECT 1 FROM foo

You can also provide a method name and arguments to call to get the SQL:

DB[:items].with_sql(:insert_sql, :b=>1) # INSERT INTO items (b) VALUES (1)

Note that datasets that specify custom SQL using this method will generally ignore future dataset methods that modify the SQL used, as specifying custom SQL overrides Sequel's SQL generator. You should probably limit yourself to the following dataset methods when using this method, or use the implicit_subquery extension:

  • each

  • all

  • single_record (if only one record could be returned)

  • single_value (if only one record could be returned, and a single column is selected)

  • map

  • as_hash

  • to_hash

  • to_hash_groups

  • delete (if a DELETE statement)

  • update (if an UPDATE statement, with no arguments)

  • insert (if an INSERT statement, with no arguments)

  • truncate (if a TRUNCATE statement, with no arguments)

     # File lib/sequel/dataset/query.rb
1156 def with_sql(sql, *args)
1157   if sql.is_a?(Symbol)
1158     sql = public_send(sql, *args)
1159   else
1160     sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
1161   end
1162   clone(:sql=>sql)
1163 end

Protected Instance Methods

compound_clone(type, dataset, opts) click to toggle source

Add the dataset to the list of compounds

     # File lib/sequel/dataset/query.rb
1168 def compound_clone(type, dataset, opts)
1169   if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds?
1170     s, ds = hoist_cte(dataset)
1171     return s.compound_clone(type, ds, opts)
1172   end
1173   ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze)
1174   opts[:from_self] == false ? ds : ds.from_self(opts)
1175 end
options_overlap(opts) click to toggle source

Return true if the dataset has a non-nil value for any key in opts.

     # File lib/sequel/dataset/query.rb
1178 def options_overlap(opts)
1179   !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty?
1180 end
simple_select_all?() click to toggle source

Whether this dataset is a simple select from an underlying table, such as:

SELECT * FROM table
SELECT table.* FROM table
     # File lib/sequel/dataset/query.rb
1189 def simple_select_all?
1190   return false unless (f = @opts[:from]) && f.length == 1
1191   o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)}
1192   from = f.first
1193   from = from.expression if from.is_a?(SQL::AliasedExpression)
1194 
1195   if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)}
1196     case o.length
1197     when 1
1198       true
1199     when 2
1200       (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1201     else
1202       false
1203     end
1204   else
1205     false
1206   end
1207 end

Private Instance Methods

_extension!(exts) click to toggle source

Load the extensions into the receiver, without checking if the receiver is frozen.

     # File lib/sequel/dataset/query.rb
1212 def _extension!(exts)
1213   Sequel.extension(*exts)
1214   exts.each do |ext|
1215     if pr = Sequel.synchronize{EXTENSIONS[ext]}
1216       pr.call(self)
1217     else
1218       raise(Error, "Extension #{ext} does not have specific support handling individual datasets (try: Sequel.extension #{ext.inspect})")
1219     end
1220   end
1221   self
1222 end
add_filter(clause, cond, invert=false, combine=:AND, &block) click to toggle source
     # File lib/sequel/dataset/query.rb
1224 def add_filter(clause, cond, invert=false, combine=:AND, &block)
1225   if cond == EMPTY_ARRAY && !block
1226     raise Error, "must provide an argument to a filtering method if not passing a block"
1227   end
1228   
1229   cond = cond.first if cond.size == 1
1230 
1231   empty = cond == OPTS || cond == EMPTY_ARRAY
1232 
1233   if empty && !block
1234     self 
1235   else
1236     if cond == nil
1237       cond = Sequel::NULL
1238     end
1239     if empty && block
1240       cond = nil
1241     end
1242 
1243     cond = filter_expr(cond, &block)
1244     cond = SQL::BooleanExpression.invert(cond) if invert
1245     cond = SQL::BooleanExpression.new(combine, @opts[clause], cond) if @opts[clause]
1246 
1247     if cond.nil?
1248       cond = Sequel::NULL
1249     end
1250 
1251     clone(clause => cond)
1252   end
1253 end
default_join_table_qualification() click to toggle source

The default :qualify option to use for join tables if one is not specified.

     # File lib/sequel/dataset/query.rb
1256 def default_join_table_qualification
1257   :symbol
1258 end
default_server() click to toggle source

Return self if the dataset already has a server, or a cloned dataset with the default server otherwise.

     # File lib/sequel/dataset/query.rb
1331 def default_server
1332   server?(:default)
1333 end
filter_expr(expr = nil, &block) click to toggle source

SQL expression object based on the expr type. See where.

     # File lib/sequel/dataset/query.rb
1261 def filter_expr(expr = nil, &block)
1262   expr = nil if expr == EMPTY_ARRAY
1263 
1264   if block
1265     cond = filter_expr(Sequel.virtual_row(&block))
1266     cond = SQL::BooleanExpression.new(:AND, filter_expr(expr), cond) if expr
1267     return cond
1268   end
1269 
1270   case expr
1271   when Hash
1272     SQL::BooleanExpression.from_value_pairs(expr)
1273   when Array
1274     if Sequel.condition_specifier?(expr)
1275       SQL::BooleanExpression.from_value_pairs(expr)
1276     else
1277       raise Error, "Invalid filter expression: #{expr.inspect}"
1278     end
1279   when LiteralString
1280     LiteralString.new("(#{expr})")
1281   when Numeric, SQL::NumericExpression, SQL::StringExpression, Proc, String
1282     raise Error, "Invalid filter expression: #{expr.inspect}"
1283   when TrueClass, FalseClass
1284     if supports_where_true?
1285       SQL::BooleanExpression.new(:NOOP, expr)
1286     elsif expr
1287       SQL::Constants::SQLTRUE
1288     else
1289       SQL::Constants::SQLFALSE
1290     end
1291   when PlaceholderLiteralizer::Argument
1292     expr.transform{|v| filter_expr(v)}
1293   when SQL::PlaceholderLiteralString
1294     expr.with_parens
1295   else
1296     expr
1297   end
1298 end
hoist_cte(ds) click to toggle source

Return two datasets, the first a clone of the receiver with the WITH clause from the given dataset added to it, and the second a clone of the given dataset with the WITH clause removed.

     # File lib/sequel/dataset/query.rb
1303 def hoist_cte(ds)
1304   [clone(:with => ((opts[:with] || EMPTY_ARRAY) + ds.opts[:with]).freeze), ds.clone(:with => nil)]
1305 end
hoist_cte?(ds) click to toggle source

Whether CTEs need to be hoisted from the given ds into the current ds.

     # File lib/sequel/dataset/query.rb
1308 def hoist_cte?(ds)
1309   ds.is_a?(Dataset) && ds.opts[:with] && !supports_cte_in_subqueries?
1310 end
invert_order(order) click to toggle source

Inverts the given order by breaking it into a list of column references and inverting them.

DB[:items].invert_order([Sequel.desc(:id)]]) #=> [Sequel.asc(:id)]
DB[:items].invert_order([:category, Sequel.desc(:price)]) #=> [Sequel.desc(:category), Sequel.asc(:price)]
     # File lib/sequel/dataset/query.rb
1317 def invert_order(order)
1318   return unless order
1319   order.map do |f|
1320     case f
1321     when SQL::OrderedExpression
1322       f.invert
1323     else
1324       SQL::OrderedExpression.new(f)
1325     end
1326   end
1327 end
non_sql_option?(key) click to toggle source

Whether the given option key does not affect the generated SQL.

     # File lib/sequel/dataset/query.rb
1336 def non_sql_option?(key)
1337   NON_SQL_OPTIONS.include?(key)
1338 end
virtual_row_columns(columns, block) click to toggle source

Treat the block as a virtual_row block if not nil and add the resulting columns to the columns array (modifies columns).

     # File lib/sequel/dataset/query.rb
1342 def virtual_row_columns(columns, block)
1343   if block
1344     v = Sequel.virtual_row(&block)
1345     if v.is_a?(Array)
1346       columns.concat(v)
1347     else
1348       columns << v
1349     end
1350   end
1351 end

2 - Methods that execute code on the database

↑ top

Constants

ACTION_METHODS

Action methods defined by Sequel that execute code on the database.

COLUMNS_CLONE_OPTIONS

The clone options to use when retriveing columns for a dataset.

COUNT_SELECT
EMPTY_SELECT

Public Instance Methods

<<(arg) click to toggle source

Inserts the given argument into the database. Returns self so it can be used safely when chaining:

DB[:items] << {id: 0, name: 'Zero'} << DB[:old_items].select(:id, name)
   # File lib/sequel/dataset/actions.rb
28 def <<(arg)
29   insert(arg)
30   self
31 end
[](*conditions) click to toggle source

Returns the first record matching the conditions. Examples:

DB[:table][id: 1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=>1}
   # File lib/sequel/dataset/actions.rb
37 def [](*conditions)
38   raise(Error, 'You cannot call Dataset#[] with an integer or with no arguments') if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
39   first(*conditions)
40 end
all(&block) click to toggle source

Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.

DB[:table].all # SELECT * FROM table
# => [{:id=>1, ...}, {:id=>2, ...}, ...]

# Iterate over all rows in the table
DB[:table].all{|row| p row}
   # File lib/sequel/dataset/actions.rb
50 def all(&block)
51   _all(block){|a| each{|r| a << r}}
52 end
as_hash(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].as_hash(:id, :name) # SELECT * FROM table
# {1=>'Jim', 2=>'Bob', ...}

DB[:table].as_hash(:id) # SELECT * FROM table
# {1=>{:id=>1, :name=>'Jim'}, 2=>{:id=>2, :name=>'Bob'}, ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].as_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...}

DB[:table].as_hash([:id, :name]) # SELECT * FROM table
# {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob']=>{:id=>2, :name=>'Bob'}, ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
764 def as_hash(key_column, value_column = nil, opts = OPTS)
765   h = opts[:hash] || {}
766   meth = opts[:all] ? :all : :each
767   if value_column
768     return naked.as_hash(key_column, value_column, opts) if row_proc
769     if value_column.is_a?(Array)
770       if key_column.is_a?(Array)
771         public_send(meth){|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
772       else
773         public_send(meth){|r| h[r[key_column]] = r.values_at(*value_column)}
774       end
775     else
776       if key_column.is_a?(Array)
777         public_send(meth){|r| h[r.values_at(*key_column)] = r[value_column]}
778       else
779         public_send(meth){|r| h[r[key_column]] = r[value_column]}
780       end
781     end
782   elsif key_column.is_a?(Array)
783     public_send(meth){|r| h[key_column.map{|k| r[k]}] = r}
784   else
785     public_send(meth){|r| h[r[key_column]] = r}
786   end
787   h
788 end
avg(arg=Sequel.virtual_row(&Proc.new)) click to toggle source

Returns the average value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1
# => 3
DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1
# => 1
   # File lib/sequel/dataset/actions.rb
61 def avg(arg=Sequel.virtual_row(&Proc.new))
62   _aggregate(:avg, arg)
63 end
columns() click to toggle source

Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.

If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema.

DB[:table].columns
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
74 def columns
75   _columns || columns!
76 end
columns!() click to toggle source

Ignore any cached column information and perform a query to retrieve a row in order to get the columns.

DB[:table].columns!
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
83 def columns!
84   ds = clone(COLUMNS_CLONE_OPTIONS)
85   ds.each{break}
86 
87   if cols = ds.cache[:_columns]
88     self.columns = cols
89   else
90     []
91   end
92 end
count(arg=(no_arg=true), &block) click to toggle source

Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.

DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1
# => 3
DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1
# => 2
DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1
# => 1
    # File lib/sequel/dataset/actions.rb
107 def count(arg=(no_arg=true), &block)
108   if no_arg && !block
109     cached_dataset(:_count_ds) do
110       aggregate_dataset.select(COUNT_SELECT).single_value_ds
111     end.single_value!.to_i
112   else
113     if block
114       if no_arg
115         arg = Sequel.virtual_row(&block)
116       else
117         raise Error, 'cannot provide both argument and block to Dataset#count'
118       end
119     end
120 
121     _aggregate(:count, arg)
122   end
123 end
delete(&block) click to toggle source

Deletes the records in the dataset, returning the number of records deleted.

DB[:table].delete # DELETE * FROM table
# => 3
    # File lib/sequel/dataset/actions.rb
129 def delete(&block)
130   sql = delete_sql
131   if uses_returning?(:delete)
132     returning_fetch_rows(sql, &block)
133   else
134     execute_dui(sql)
135   end
136 end
each() { |call| ... } click to toggle source

Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.

DB[:table].each{|row| p row} # SELECT * FROM table

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all instead of each for the outer queries, or use a separate thread or shard inside each.

    # File lib/sequel/dataset/actions.rb
147 def each
148   if rp = row_proc
149     fetch_rows(select_sql){|r| yield rp.call(r)}
150   else
151     fetch_rows(select_sql){|r| yield r}
152   end
153   self
154 end
empty?() click to toggle source

Returns true if no records exist in the dataset, false otherwise

DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
# => false
    # File lib/sequel/dataset/actions.rb
162 def empty?
163   cached_dataset(:_empty_ds) do
164     single_value_ds.unordered.select(EMPTY_SELECT)
165   end.single_value!.nil?
166 end
first(*args, &block) click to toggle source

Returns the first matching record if no arguments are given. If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If any other type of argument(s) is passed, it is treated as a filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything.

If there are no records in the dataset, returns nil (or an empty array if an integer argument is given).

Examples:

DB[:table].first # SELECT * FROM table LIMIT 1
# => {:id=>7}

DB[:table].first(2) # SELECT * FROM table LIMIT 2
# => [{:id=>6}, {:id=>4}]

DB[:table].first(id: 2) # SELECT * FROM table WHERE (id = 2) LIMIT 1
# => {:id=>2}

DB[:table].first(Sequel.lit("id = 3")) # SELECT * FROM table WHERE (id = 3) LIMIT 1
# => {:id=>3}

DB[:table].first(Sequel.lit("id = ?", 4)) # SELECT * FROM table WHERE (id = 4) LIMIT 1
# => {:id=>4}

DB[:table].first{id > 2} # SELECT * FROM table WHERE (id > 2) LIMIT 1
# => {:id=>5}

DB[:table].first(Sequel.lit("id > ?", 4)){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1
# => {:id=>5}

DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2
# => [{:id=>1}]
    # File lib/sequel/dataset/actions.rb
203 def first(*args, &block)
204   case args.length
205   when 0
206     unless block
207       return single_record
208     end
209   when 1
210     arg = args[0]
211     if arg.is_a?(Integer)
212       res = if block
213         if loader = cached_placeholder_literalizer(:_first_integer_cond_loader) do |pl|
214             where(pl.arg).limit(pl.arg)
215           end
216 
217           loader.all(filter_expr(&block), arg)
218         else
219           where(&block).limit(arg).all
220         end
221       else
222         if loader = cached_placeholder_literalizer(:_first_integer_loader) do |pl|
223            limit(pl.arg)
224           end
225 
226           loader.all(arg)
227         else
228           limit(arg).all
229         end
230       end
231 
232       return res
233     end
234     args = arg
235   end
236 
237   if loader = cached_placeholder_literalizer(:_first_cond_loader) do |pl|
238       _single_record_ds.where(pl.arg)
239     end
240 
241     loader.first(filter_expr(args, &block))
242   else
243     _single_record_ds.where(args, &block).single_record!
244   end
245 end
first!(*args, &block) click to toggle source

Calls first. If first returns nil (signaling that no row matches), raise a Sequel::NoMatchingRow exception.

    # File lib/sequel/dataset/actions.rb
249 def first!(*args, &block)
250   first(*args, &block) || raise(Sequel::NoMatchingRow.new(self))
251 end
get(column=(no_arg=true; nil), &block) click to toggle source

Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.

DB[:table].get(:id) # SELECT id FROM table LIMIT 1
# => 3

ds.get{sum(id)} # SELECT sum(id) AS v FROM table LIMIT 1
# => 6

You can pass an array of arguments to return multiple arguments, but you must make sure each element in the array has an alias that Sequel can determine:

DB[:table].get([:id, :name]) # SELECT id, name FROM table LIMIT 1
# => [3, 'foo']

DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1
# => [6, 'foo']
    # File lib/sequel/dataset/actions.rb
271 def get(column=(no_arg=true; nil), &block)
272   ds = naked
273   if block
274     raise(Error, 'Must call Dataset#get with an argument or a block, not both') unless no_arg
275     ds = ds.select(&block)
276     column = ds.opts[:select]
277     column = nil if column.is_a?(Array) && column.length < 2
278   else
279     case column
280     when Array
281       ds = ds.select(*column)
282     when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
283       if loader = cached_placeholder_literalizer(:_get_loader) do |pl|
284           ds.single_value_ds.select(pl.arg)
285         end
286 
287         return loader.get(column)
288       end
289 
290       ds = ds.select(column)
291     else
292       if loader = cached_placeholder_literalizer(:_get_alias_loader) do |pl|
293           ds.single_value_ds.select(Sequel.as(pl.arg, :v))
294         end
295 
296         return loader.get(column)
297       end
298 
299       ds = ds.select(Sequel.as(column, :v))
300     end
301   end
302 
303   if column.is_a?(Array)
304    if r = ds.single_record
305      r.values_at(*hash_key_symbols(column))
306    end
307   else
308     ds.single_value
309   end
310 end
import(columns, values, opts=OPTS) click to toggle source

Inserts multiple records into the associated table. This method can be used to efficiently insert a large number of records into a table in a single query if the database supports it. Inserts are automatically wrapped in a transaction.

This method is called with a columns array and an array of value arrays:

DB[:table].import([:x, :y], [[1, 2], [3, 4]])
# INSERT INTO table (x, y) VALUES (1, 2)
# INSERT INTO table (x, y) VALUES (3, 4)

This method also accepts a dataset instead of an array of value arrays:

DB[:table].import([:x, :y], DB[:table2].select(:a, :b))
# INSERT INTO table (x, y) SELECT a, b FROM table2

Options:

:commit_every

Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records.

:return

When this is set to :primary_key, returns an array of autoincremented primary key values for the rows inserted.

:server

Set the server/shard to use for the transaction and insert queries.

:slice

Same as :commit_every, :commit_every takes precedence.

    # File lib/sequel/dataset/actions.rb
337 def import(columns, values, opts=OPTS)
338   return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
339 
340   return if values.empty?
341   raise(Error, 'Using Sequel::Dataset#import with an empty column array is not allowed') if columns.empty?
342   ds = opts[:server] ? server(opts[:server]) : self
343   
344   if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
345     offset = 0
346     rows = []
347     while offset < values.length
348       rows << ds._import(columns, values[offset, slice_size], opts)
349       offset += slice_size
350     end
351     rows.flatten
352   else
353     ds._import(columns, values, opts)
354   end
355 end
insert(*values, &block) click to toggle source

Inserts values into the associated table. The returned value is generally the value of the autoincremented primary key for the inserted row, assuming that the a single row is inserted and the table has an autoincrementing primary key.

insert handles a number of different argument formats:

no arguments or single empty hash

Uses DEFAULT VALUES

single hash

Most common format, treats keys as columns and values as values

single array

Treats entries as values, with no columns

two arrays

Treats first array as columns, second array as values

single Dataset

Treats as an insert based on a selection from the dataset given, with no columns

array and dataset

Treats as an insert based on a selection from the dataset given, with the columns given by the array.

Examples:

DB[:items].insert
# INSERT INTO items DEFAULT VALUES

DB[:items].insert({})
# INSERT INTO items DEFAULT VALUES

DB[:items].insert([1,2,3])
# INSERT INTO items VALUES (1, 2, 3)

DB[:items].insert([:a, :b], [1,2])
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(a: 1, b: 2)
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(DB[:old_items])
# INSERT INTO items SELECT * FROM old_items

DB[:items].insert([:a, :b], DB[:old_items])
# INSERT INTO items (a, b) SELECT * FROM old_items
    # File lib/sequel/dataset/actions.rb
393 def insert(*values, &block)
394   sql = insert_sql(*values)
395   if uses_returning?(:insert)
396     returning_fetch_rows(sql, &block)
397   else
398     execute_insert(sql)
399   end
400 end
last(*args, &block) click to toggle source

Reverses the order and then runs first with the given arguments and block. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error.

DB[:table].order(:id).last # SELECT * FROM table ORDER BY id DESC LIMIT 1
# => {:id=>10}

DB[:table].order(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
# => [{:id=>1}, {:id=>2}]
    # File lib/sequel/dataset/actions.rb
412 def last(*args, &block)
413   raise(Error, 'No order specified') unless @opts[:order]
414   reverse.first(*args, &block)
415 end
map(column=nil, &block) click to toggle source

Maps column values for each record in the dataset (if an argument is given) or performs the stock mapping functionality of Enumerable otherwise. Raises an Error if both an argument and block are given.

DB[:table].map(:id) # SELECT * FROM table
# => [1, 2, 3, ...]

DB[:table].map{|r| r[:id] * 2} # SELECT * FROM table
# => [2, 4, 6, ...]

You can also provide an array of column names:

DB[:table].map([:id, :name]) # SELECT * FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
Calls superclass method
    # File lib/sequel/dataset/actions.rb
431 def map(column=nil, &block)
432   if column
433     raise(Error, 'Must call Dataset#map with either an argument or a block, not both') if block
434     return naked.map(column) if row_proc
435     if column.is_a?(Array)
436       super(){|r| r.values_at(*column)}
437     else
438       super(){|r| r[column]}
439     end
440   else
441     super(&block)
442   end
443 end
max(arg=Sequel.virtual_row(&Proc.new)) click to toggle source

Returns the maximum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
# => 10
DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1
# => 7
    # File lib/sequel/dataset/actions.rb
452 def max(arg=Sequel.virtual_row(&Proc.new))
453   _aggregate(:max, arg)
454 end
min(arg=Sequel.virtual_row(&Proc.new)) click to toggle source

Returns the minimum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1
# => 1
DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1
# => 0
    # File lib/sequel/dataset/actions.rb
463 def min(arg=Sequel.virtual_row(&Proc.new))
464   _aggregate(:min, arg)
465 end
multi_insert(hashes, opts=OPTS) click to toggle source

This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:

DB[:table].multi_insert([{x: 1}, {x: 2}])
# INSERT INTO table (x) VALUES (1)
# INSERT INTO table (x) VALUES (2)

Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.

This respects the same options as import.

    # File lib/sequel/dataset/actions.rb
479 def multi_insert(hashes, opts=OPTS)
480   return if hashes.empty?
481   columns = hashes.first.keys
482   import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
483 end
paged_each(opts=OPTS) { |row| ... } click to toggle source

Yields each row in the dataset, but interally uses multiple queries as needed to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.

Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to work correctly, the dataset must have unambiguous order. Using an ambiguous order can result in an infinite loop, as well as subtler bugs such as yielding duplicate rows or rows being skipped.

Sequel checks that the datasets using this method have an order, but it cannot ensure that the order is unambiguous.

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, use a separate thread or shard inside paged_each.

Options:

:rows_per_fetch

The number of rows to fetch per query. Defaults to 1000.

:strategy

The strategy to use for paging of results. By default this is :offset, for using an approach with a limit and offset for every page. This can be set to :filter, which uses a limit and a filter that excludes rows from previous pages. In order for this strategy to work, you must be selecting the columns you are ordering by, and none of the columns can contain NULLs. Note that some Sequel adapters have optimized implementations that will use cursors or streaming regardless of the :strategy option used.

:filter_values

If the strategy: :filter option is used, this option should be a proc that accepts the last retreived row for the previous page and an array of ORDER BY expressions, and returns an array of values relating to those expressions for the last retrieved row. You will need to use this option if your ORDER BY expressions are not simple columns, if they contain qualified identifiers that would be ambiguous unqualified, if they contain any identifiers that are aliased in SELECT, and potentially other cases.

Examples:

DB[:table].order(:id).paged_each{|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table ORDER BY id LIMIT 1000 OFFSET 1000
# ...

DB[:table].order(:id).paged_each(:rows_per_fetch=>100){|row| }
# SELECT * FROM table ORDER BY id LIMIT 100
# SELECT * FROM table ORDER BY id LIMIT 100 OFFSET 100
# ...

DB[:table].order(:id).paged_each(strategy: :filter){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...

DB[:table].order(:id).paged_each(strategy: :filter,
  filter_values: lambda{|row, exprs| [row[:id]]}){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...
    # File lib/sequel/dataset/actions.rb
540 def paged_each(opts=OPTS)
541   unless @opts[:order]
542     raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
543   end
544   unless block_given?
545     return enum_for(:paged_each, opts)
546   end
547 
548   total_limit = @opts[:limit]
549   offset = @opts[:offset]
550   if server = @opts[:server]
551     opts = Hash[opts]
552     opts[:server] = server
553   end
554 
555   rows_per_fetch = opts[:rows_per_fetch] || 1000
556   strategy = if offset || total_limit
557     :offset
558   else
559     opts[:strategy] || :offset
560   end
561 
562   db.transaction(opts) do
563     case strategy
564     when :filter
565       filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
566       base_ds = ds = limit(rows_per_fetch)
567       while ds
568         last_row = nil
569         ds.each do |row|
570           last_row = row
571           yield row
572         end
573         ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
574       end
575     else
576       offset ||= 0
577       num_rows_yielded = rows_per_fetch
578       total_rows = 0
579 
580       while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
581         if total_limit && total_rows + rows_per_fetch > total_limit
582           rows_per_fetch = total_limit - total_rows
583         end
584 
585         num_rows_yielded = 0
586         limit(rows_per_fetch, offset).each do |row|
587           num_rows_yielded += 1
588           total_rows += 1 if total_limit
589           yield row
590         end
591 
592         offset += rows_per_fetch
593       end
594     end
595   end
596 
597   self
598 end
select_hash(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and value_column values as values. Similar to as_hash, but only selects the columns given. Like as_hash, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash(:id, :name) # SELECT id, name FROM table
# => {1=>'a', 2=>'b', ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['a', 'c'], [2, 4]=>['b', 'd'], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
616 def select_hash(key_column, value_column, opts = OPTS)
617   _select_hash(:as_hash, key_column, value_column, opts)
618 end
select_hash_groups(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and an array of value_column values. Similar to to_hash_groups, but only selects the columns given. Like to_hash_groups, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash_groups(:name, :id) # SELECT id, name FROM table
# => {'a'=>[1, 4, ...], 'b'=>[2, ...], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash_groups([:first, :middle], [:last, :id]) # SELECT * FROM table
# {['a', 'b']=>[['c', 1], ['d', 2], ...], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
635 def select_hash_groups(key_column, value_column, opts = OPTS)
636   _select_hash(:to_hash_groups, key_column, value_column, opts)
637 end
select_map(column=nil, &block) click to toggle source

Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset. If you give a block argument that returns an array with multiple entries, the contents of the resulting array are undefined. Raises an Error if called with both an argument and a block.

DB[:table].select_map(:id) # SELECT id FROM table
# => [3, 5, 8, 1, ...]

DB[:table].select_map{id * 2} # SELECT (id * 2) FROM table
# => [6, 10, 16, 2, ...]

You can also provide an array of column names:

DB[:table].select_map([:id, :name]) # SELECT id, name FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
658 def select_map(column=nil, &block)
659   _select_map(column, false, &block)
660 end
select_order_map(column=nil, &block) click to toggle source

The same as select_map, but in addition orders the array by the column.

DB[:table].select_order_map(:id) # SELECT id FROM table ORDER BY id
# => [1, 2, 3, 4, ...]

DB[:table].select_order_map{id * 2} # SELECT (id * 2) FROM table ORDER BY (id * 2)
# => [2, 4, 6, 8, ...]

You can also provide an array of column names:

DB[:table].select_order_map([:id, :name]) # SELECT id, name FROM table ORDER BY id, name
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
677 def select_order_map(column=nil, &block)
678   _select_map(column, true, &block)
679 end
single_record() click to toggle source

Limits the dataset to one record, and returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method. Example:

DB[:test].single_record # SELECT * FROM test LIMIT 1
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
687 def single_record
688   _single_record_ds.single_record!
689 end
single_record!() click to toggle source

Returns the first record in dataset, without limiting the dataset. Returns nil if the dataset has no records. Users should probably use first instead of this method. This should only be used if you know the dataset is already limited to a single record. This method may be desirable to use for performance reasons, as it does not clone the receiver. Example:

DB[:test].single_record! # SELECT * FROM test
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
699 def single_record!
700   with_sql_first(select_sql)
701 end
single_value() click to toggle source

Returns the first value of the first record in the dataset. Returns nil if dataset is empty. Users should generally use get instead of this method. Example:

DB[:test].single_value # SELECT * FROM test LIMIT 1
# => 'value'
    # File lib/sequel/dataset/actions.rb
709 def single_value
710   single_value_ds.each do |r|
711     r.each{|_, v| return v}
712   end
713   nil
714 end
single_value!() click to toggle source

Returns the first value of the first record in the dataset, without limiting the dataset. Returns nil if the dataset is empty. Users should generally use get instead of this method. Should not be used on graphed datasets or datasets that have row_procs that don't return hashes. This method may be desirable to use for performance reasons, as it does not clone the receiver.

DB[:test].single_value! # SELECT * FROM test
# => 'value'
    # File lib/sequel/dataset/actions.rb
724 def single_value!
725   with_sql_single_value(select_sql)
726 end
sum(arg=Sequel.virtual_row(&Proc.new)) click to toggle source

Returns the sum for the given column/expression. Uses a virtual row block if no column is given.

DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
# => 55
DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1
# => 10
    # File lib/sequel/dataset/actions.rb
735 def sum(arg=Sequel.virtual_row(&Proc.new))
736   _aggregate(:sum, arg)
737 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

    # File lib/sequel/dataset/actions.rb
791 def to_hash(*a)
792   as_hash(*a)
793 end
to_hash_groups(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and the values being an array of column values. If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].to_hash_groups(:name, :id) # SELECT * FROM table
# {'Jim'=>[1, 4, 16, ...], 'Bob'=>[2], ...}

DB[:table].to_hash_groups(:name) # SELECT * FROM table
# {'Jim'=>[{:id=>1, :name=>'Jim'}, {:id=>4, :name=>'Jim'}, ...], 'Bob'=>[{:id=>2, :name=>'Bob'}], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].to_hash_groups([:first, :middle], [:last, :id]) # SELECT * FROM table
# {['Jim', 'Bob']=>[['Smith', 1], ['Jackson', 4], ...], ...}

DB[:table].to_hash_groups([:first, :middle]) # SELECT * FROM table
# {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
819 def to_hash_groups(key_column, value_column = nil, opts = OPTS)
820   h = opts[:hash] || {}
821   meth = opts[:all] ? :all : :each
822   if value_column
823     return naked.to_hash_groups(key_column, value_column, opts) if row_proc
824     if value_column.is_a?(Array)
825       if key_column.is_a?(Array)
826         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
827       else
828         public_send(meth){|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
829       end
830     else
831       if key_column.is_a?(Array)
832         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
833       else
834         public_send(meth){|r| (h[r[key_column]] ||= []) << r[value_column]}
835       end
836     end
837   elsif key_column.is_a?(Array)
838     public_send(meth){|r| (h[key_column.map{|k| r[k]}] ||= []) << r}
839   else
840     public_send(meth){|r| (h[r[key_column]] ||= []) << r}
841   end
842   h
843 end
truncate() click to toggle source

Truncates the dataset. Returns nil.

DB[:table].truncate # TRUNCATE table
# => nil
    # File lib/sequel/dataset/actions.rb
849 def truncate
850   execute_ddl(truncate_sql)
851 end
update(values=OPTS, &block) click to toggle source

Updates values for the dataset. The returned value is the number of rows updated. values should be a hash where the keys are columns to set and values are the values to which to set the columns.

DB[:table].update(x: nil) # UPDATE table SET x = NULL
# => 10

DB[:table].update(x: Sequel[:x]+1, y: 0) # UPDATE table SET x = (x + 1), y = 0
# => 10
    # File lib/sequel/dataset/actions.rb
862 def update(values=OPTS, &block)
863   sql = update_sql(values)
864   if uses_returning?(:update)
865     returning_fetch_rows(sql, &block)
866   else
867     execute_dui(sql)
868   end
869 end
where_all(cond, &block) click to toggle source

Return an array of all rows matching the given filter condition, also yielding each row to the given block. Basically the same as where(cond).all(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_all(id: [1,2,3])
# SELECT * FROM table WHERE (id IN (1, 2, 3))
    # File lib/sequel/dataset/actions.rb
877 def where_all(cond, &block)
878   if loader = _where_loader
879     loader.all(filter_expr(cond), &block)
880   else
881     where(cond).all(&block)
882   end
883 end
where_each(cond, &block) click to toggle source

Iterate over all rows matching the given filter condition, yielding each row to the given block. Basically the same as where(cond).each(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_each(id: [1,2,3]){|row| p row}
# SELECT * FROM table WHERE (id IN (1, 2, 3))
    # File lib/sequel/dataset/actions.rb
891 def where_each(cond, &block)
892   if loader = _where_loader
893     loader.each(filter_expr(cond), &block)
894   else
895     where(cond).each(&block)
896   end
897 end
where_single_value(cond) click to toggle source

Filter the datasets using the given filter condition, then return a single value. This assumes that the dataset has already been setup to limit the selection to a single column. Basically the same as where(cond).single_value, except it can be optimized to not create an intermediate dataset.

DB[:table].select(:name).where_single_value(id: 1)
# SELECT name FROM table WHERE (id = 1) LIMIT 1
    # File lib/sequel/dataset/actions.rb
906 def where_single_value(cond)
907   if loader = cached_placeholder_literalizer(:_where_single_value_loader) do |pl|
908       single_value_ds.where(pl.arg)
909     end
910 
911     loader.get(filter_expr(cond))
912   else
913     where(cond).single_value
914   end
915 end
with_sql_all(sql, &block) click to toggle source

Run the given SQL and return an array of all rows. If a block is given, each row is yielded to the block after all rows are loaded. See with_sql_each.

    # File lib/sequel/dataset/actions.rb
919 def with_sql_all(sql, &block)
920   _all(block){|a| with_sql_each(sql){|r| a << r}}
921 end
with_sql_delete(sql) click to toggle source

Execute the given SQL and return the number of rows deleted. This exists solely as an optimization, replacing with_sql(sql).delete. It's significantly faster as it does not require cloning the current dataset.

    # File lib/sequel/dataset/actions.rb
926 def with_sql_delete(sql)
927   execute_dui(sql)
928 end
Also aliased as: with_sql_update
with_sql_each(sql) { |call| ... } click to toggle source

Run the given SQL and yield each returned row to the block.

    # File lib/sequel/dataset/actions.rb
932 def with_sql_each(sql)
933   if rp = row_proc
934     _with_sql_dataset.fetch_rows(sql){|r| yield rp.call(r)}
935   else
936     _with_sql_dataset.fetch_rows(sql){|r| yield r}
937   end
938   self
939 end
with_sql_first(sql) click to toggle source

Run the given SQL and return the first row, or nil if no rows were returned. See with_sql_each.

    # File lib/sequel/dataset/actions.rb
943 def with_sql_first(sql)
944   with_sql_each(sql){|r| return r}
945   nil
946 end
with_sql_insert(sql) click to toggle source

Execute the given SQL and (on most databases) return the primary key of the inserted row.

    # File lib/sequel/dataset/actions.rb
959 def with_sql_insert(sql)
960   execute_insert(sql)
961 end
with_sql_single_value(sql) click to toggle source

Run the given SQL and return the first value in the first row, or nil if no rows were returned. For this to make sense, the SQL given should select only a single value. See with_sql_each.

    # File lib/sequel/dataset/actions.rb
951 def with_sql_single_value(sql)
952   if r = with_sql_first(sql)
953     r.each{|_, v| return v}
954   end
955 end
with_sql_update(sql)
Alias for: with_sql_delete

Protected Instance Methods

_import(columns, values, opts) click to toggle source

Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately.

    # File lib/sequel/dataset/actions.rb
968 def _import(columns, values, opts)
969   trans_opts = Hash[opts].merge!(:server=>@opts[:server])
970   if opts[:return] == :primary_key
971     @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
972   else
973     stmts = multi_insert_sql(columns, values)
974     @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
975   end
976 end
_select_map_multiple(ret_cols) click to toggle source

Return an array of arrays of values given by the symbols in ret_cols.

    # File lib/sequel/dataset/actions.rb
979 def _select_map_multiple(ret_cols)
980   map{|r| r.values_at(*ret_cols)}
981 end
_select_map_single() click to toggle source

Returns an array of the first value in each row.

    # File lib/sequel/dataset/actions.rb
984 def _select_map_single
985   k = nil
986   map{|r| r[k||=r.keys.first]}
987 end
single_value_ds() click to toggle source

A dataset for returning single values from the current dataset.

    # File lib/sequel/dataset/actions.rb
990 def single_value_ds
991   clone(:limit=>1).ungraphed.naked
992 end

Private Instance Methods

_aggregate(function, arg) click to toggle source

Cached placeholder literalizer for methods that return values using aggregate functions.

     # File lib/sequel/dataset/actions.rb
1006 def _aggregate(function, arg)
1007   if loader = cached_placeholder_literalizer(:"_#{function}_loader") do |pl|
1008         aggregate_dataset.limit(1).select(SQL::Function.new(function, pl.arg).as(function))
1009       end
1010     loader.get(arg)
1011   else
1012     aggregate_dataset.get(SQL::Function.new(function, arg).as(function))
1013   end
1014 end
_all(block) { |a| ... } click to toggle source

Internals of all and with_sql_all

     # File lib/sequel/dataset/actions.rb
 997 def _all(block)
 998   a = []
 999   yield a
1000   post_load(a)
1001   a.each(&block) if block
1002   a
1003 end
_hash_key_symbol(s, recursing=false) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Return nil if no hash key can be determined

     # File lib/sequel/dataset/actions.rb
1105 def _hash_key_symbol(s, recursing=false)
1106   case s
1107   when Symbol
1108     _, c, a = split_symbol(s)
1109     (a || c).to_sym
1110   when SQL::Identifier, SQL::Wrapper
1111     _hash_key_symbol(s.value, true)
1112   when SQL::QualifiedIdentifier
1113     _hash_key_symbol(s.column, true)
1114   when SQL::AliasedExpression
1115     _hash_key_symbol(s.alias, true)
1116   when String
1117     s.to_sym if recursing
1118   end
1119 end
_select_hash(meth, key_column, value_column, opts=OPTS) click to toggle source

Internals of select_hash and select_hash_groups

     # File lib/sequel/dataset/actions.rb
1017 def _select_hash(meth, key_column, value_column, opts=OPTS)
1018   select(*(key_column.is_a?(Array) ? key_column : [key_column]) + (value_column.is_a?(Array) ? value_column : [value_column])).
1019     public_send(meth, hash_key_symbols(key_column), hash_key_symbols(value_column), opts)
1020 end
_select_map(column, order, &block) click to toggle source

Internals of select_map and select_order_map

     # File lib/sequel/dataset/actions.rb
1023 def _select_map(column, order, &block)
1024   ds = ungraphed.naked
1025   columns = Array(column)
1026   virtual_row_columns(columns, block)
1027   select_cols = order ? columns.map{|c| c.is_a?(SQL::OrderedExpression) ? c.expression : c} : columns
1028   ds = ds.order(*columns.map{|c| unaliased_identifier(c)}) if order
1029   if column.is_a?(Array) || (columns.length > 1)
1030     ds.select(*select_cols)._select_map_multiple(hash_key_symbols(select_cols))
1031   else
1032     ds.select(auto_alias_expression(select_cols.first))._select_map_single
1033   end
1034 end
_single_record_ds() click to toggle source

A cached dataset for a single record for this dataset.

     # File lib/sequel/dataset/actions.rb
1037 def _single_record_ds
1038   cached_dataset(:_single_record_ds){clone(:limit=>1)}
1039 end
_where_loader() click to toggle source

Loader used for where_all and where_each.

     # File lib/sequel/dataset/actions.rb
1042 def _where_loader
1043   cached_placeholder_literalizer(:_where_loader) do |pl|
1044     where(pl.arg)
1045   end
1046 end
_with_sql_dataset() click to toggle source

Cached dataset to use for with_sql_#{all,each,first,single_value}. This is used so that the columns returned by the given SQL do not affect the receiver of the with_sql_* method.

     # File lib/sequel/dataset/actions.rb
1223 def _with_sql_dataset
1224   if @opts[:_with_sql_ds]
1225     self
1226   else
1227     cached_dataset(:_with_sql_ds) do
1228       clone(:_with_sql_ds=>true)
1229     end
1230   end
1231 end
auto_alias_expression(v) click to toggle source

Automatically alias the given expression if it does not have an identifiable alias.

     # File lib/sequel/dataset/actions.rb
1049 def auto_alias_expression(v)
1050   case v
1051   when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
1052     v
1053   else
1054     SQL::AliasedExpression.new(v, :v)
1055   end
1056 end
default_import_slice() click to toggle source

The default number of rows that can be inserted in a single INSERT statement via import. The default is for no limit.

     # File lib/sequel/dataset/actions.rb
1060 def default_import_slice
1061   nil
1062 end
default_server_opts(opts) click to toggle source

Set the server to use to :default unless it is already set in the passed opts

     # File lib/sequel/dataset/actions.rb
1065 def default_server_opts(opts)
1066   if @db.sharded?
1067     opts = Hash[opts]
1068     opts[:server] = @opts[:server] || :default
1069   end
1070   opts
1071 end
execute(sql, opts=OPTS, &block) click to toggle source

Execute the given select SQL on the database using execute. Use the :read_only server unless a specific server is set.

     # File lib/sequel/dataset/actions.rb
1075 def execute(sql, opts=OPTS, &block)
1076   db = @db
1077   if db.sharded?
1078     opts = Hash[opts]
1079     opts[:server] = @opts[:server] || (@opts[:lock] ? :default : :read_only)
1080     opts
1081   end
1082   db.execute(sql, opts, &block)
1083 end
execute_ddl(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_ddl.

     # File lib/sequel/dataset/actions.rb
1086 def execute_ddl(sql, opts=OPTS, &block)
1087   @db.execute_ddl(sql, default_server_opts(opts), &block)
1088   nil
1089 end
execute_dui(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_dui.

     # File lib/sequel/dataset/actions.rb
1092 def execute_dui(sql, opts=OPTS, &block)
1093   @db.execute_dui(sql, default_server_opts(opts), &block)
1094 end
execute_insert(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_insert.

     # File lib/sequel/dataset/actions.rb
1097 def execute_insert(sql, opts=OPTS, &block)
1098   @db.execute_insert(sql, default_server_opts(opts), &block)
1099 end
hash_key_symbol(s) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Raise Error if the hash key symbol cannot be returned.

     # File lib/sequel/dataset/actions.rb
1125 def hash_key_symbol(s)
1126   if v = _hash_key_symbol(s)
1127     v
1128   else
1129     raise(Error, "#{s.inspect} is not supported, should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression")
1130   end
1131 end
hash_key_symbols(s) click to toggle source

If s is an array, return an array with the given hash key symbols. Otherwise, return a hash key symbol for the given expression If a hash key symbol cannot be determined, raise an error.

     # File lib/sequel/dataset/actions.rb
1136 def hash_key_symbols(s)
1137   s.is_a?(Array) ? s.map{|c| hash_key_symbol(c)} : hash_key_symbol(s)
1138 end
ignore_values_preceding(row) { |row, map(&:first)| ... } click to toggle source

Returns an expression that will ignore values preceding the given row, using the receiver's current order. This yields the row and the array of order expressions to the block, which should return an array of values to use.

     # File lib/sequel/dataset/actions.rb
1143 def ignore_values_preceding(row)
1144   @opts[:order].map{|v| v.is_a?(SQL::OrderedExpression) ? v.expression : v}
1145 
1146   order_exprs = @opts[:order].map do |v|
1147     if v.is_a?(SQL::OrderedExpression)
1148       descending = v.descending
1149       v = v.expression
1150     else
1151       descending = false
1152     end
1153     [v, descending]
1154   end
1155 
1156   row_values = yield(row, order_exprs.map(&:first))
1157 
1158   last_expr = []
1159   cond = order_exprs.zip(row_values).map do |(v, descending), value|
1160     expr =  last_expr + [SQL::BooleanExpression.new(descending ? :< : :>, v, value)]
1161     last_expr += [SQL::BooleanExpression.new(:'=', v, value)]
1162     Sequel.&(*expr)
1163   end
1164   Sequel.|(*cond)
1165 end
output_identifier(v) click to toggle source

Downcase identifiers by default when outputing them from the database.

     # File lib/sequel/dataset/actions.rb
1168 def output_identifier(v)
1169   v = 'untitled' if v == ''
1170   v.to_s.downcase.to_sym
1171 end
post_load(all_records) click to toggle source

This is run inside .all, after all of the records have been loaded via .each, but before any block passed to all is called. It is called with a single argument, an array of all returned records. Does nothing by default, added to make the model eager loading code simpler.

     # File lib/sequel/dataset/actions.rb
1177 def post_load(all_records)
1178 end
returning_fetch_rows(sql, &block) click to toggle source

Called by insert/update/delete when returning is used. Yields each row as a plain hash to the block if one is given, or returns an array of plain hashes for all rows if a block is not given

     # File lib/sequel/dataset/actions.rb
1183 def returning_fetch_rows(sql, &block)
1184   if block
1185     default_server.fetch_rows(sql, &block)
1186     nil
1187   else
1188     rows = []
1189     default_server.fetch_rows(sql){|r| rows << r}
1190     rows
1191   end
1192 end
unaliased_identifier(c) click to toggle source

Return the unaliased part of the identifier. Handles both implicit aliases in symbols, as well as SQL::AliasedExpression objects. Other objects are returned as is.

     # File lib/sequel/dataset/actions.rb
1197 def unaliased_identifier(c)
1198   case c
1199   when Symbol
1200     table, column, aliaz = split_symbol(c)
1201     if aliaz
1202       table ? SQL::QualifiedIdentifier.new(table, column) : Sequel.identifier(column)
1203     else
1204       c
1205     end
1206   when SQL::AliasedExpression
1207     c.expression
1208   when SQL::OrderedExpression
1209     case expr = c.expression
1210     when Symbol, SQL::AliasedExpression
1211       SQL::OrderedExpression.new(unaliased_identifier(expr), c.descending, :nulls=>c.nulls)
1212     else
1213       c
1214     end
1215   else
1216     c
1217   end
1218 end

3 - User Methods relating to SQL Creation

↑ top

Public Instance Methods

exists() click to toggle source

Returns an EXISTS clause for the dataset as an SQL::PlaceholderLiteralString.

DB.select(1).where(DB[:items].exists)
# SELECT 1 WHERE (EXISTS (SELECT * FROM items))
   # File lib/sequel/dataset/sql.rb
14 def exists
15   SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
16 end
insert_sql(*values) click to toggle source

Returns an INSERT SQL query string. See insert.

DB[:items].insert_sql(a: 1)
# => "INSERT INTO items (a) VALUES (1)"
   # File lib/sequel/dataset/sql.rb
22 def insert_sql(*values)
23   return static_sql(@opts[:sql]) if @opts[:sql]
24 
25   check_modification_allowed!
26 
27   columns = []
28 
29   case values.size
30   when 0
31     return insert_sql(OPTS)
32   when 1
33     case vals = values[0]
34     when Hash
35       values = []
36       vals.each do |k,v| 
37         columns << k
38         values << v
39       end
40     when Dataset, Array, LiteralString
41       values = vals
42     end
43   when 2
44     if (v0 = values[0]).is_a?(Array) && ((v1 = values[1]).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
45       columns, values = v0, v1
46       raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
47     end
48   end
49 
50   if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
51     columns, values = insert_empty_columns_values
52   elsif values.is_a?(Dataset) && hoist_cte?(values) && supports_cte?(:insert)
53     ds, values = hoist_cte(values)
54     return ds.clone(:columns=>columns, :values=>values).send(:_insert_sql)
55   end
56   clone(:columns=>columns, :values=>values).send(:_insert_sql)
57 end
literal_append(sql, v) click to toggle source

Append a literal representation of a value to the given SQL string.

If an unsupported object is given, an Error is raised.

    # File lib/sequel/dataset/sql.rb
 62 def literal_append(sql, v)
 63   case v
 64   when Symbol
 65     if skip_symbol_cache?
 66       literal_symbol_append(sql, v)
 67     else 
 68       unless l = db.literal_symbol(v)
 69         l = String.new
 70         literal_symbol_append(l, v)
 71         db.literal_symbol_set(v, l)
 72       end
 73       sql << l
 74     end
 75   when String
 76     case v
 77     when LiteralString
 78       sql << v
 79     when SQL::Blob
 80       literal_blob_append(sql, v)
 81     else
 82       literal_string_append(sql, v)
 83     end
 84   when Integer
 85     sql << literal_integer(v)
 86   when Hash
 87     literal_hash_append(sql, v)
 88   when SQL::Expression
 89     literal_expression_append(sql, v)
 90   when Float
 91     sql << literal_float(v)
 92   when BigDecimal
 93     sql << literal_big_decimal(v)
 94   when NilClass
 95     sql << literal_nil
 96   when TrueClass
 97     sql << literal_true
 98   when FalseClass
 99     sql << literal_false
100   when Array
101     literal_array_append(sql, v)
102   when Time
103     v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v)
104   when DateTime
105     literal_datetime_append(sql, v)
106   when Date
107     sql << literal_date(v)
108   when Dataset
109     literal_dataset_append(sql, v)
110   else
111     literal_other_append(sql, v)
112   end
113 end
multi_insert_sql(columns, values) click to toggle source

Returns an array of insert statements for inserting multiple records. This method is used by multi_insert to format insert statements and expects a keys array and and an array of value arrays.

    # File lib/sequel/dataset/sql.rb
118 def multi_insert_sql(columns, values)
119   case multi_insert_sql_strategy
120   when :values
121     sql = LiteralString.new('VALUES ')
122     expression_list_append(sql, values.map{|r| Array(r)})
123     [insert_sql(columns, sql)]
124   when :union
125     c = false
126     sql = LiteralString.new
127     u = ' UNION ALL SELECT '
128     f = empty_from_sql
129     values.each do |v|
130       if c
131         sql << u
132       else
133         sql << 'SELECT '
134         c = true
135       end
136       expression_list_append(sql, v)
137       sql << f if f
138     end
139     [insert_sql(columns, sql)]
140   else
141     values.map{|r| insert_sql(columns, r)}
142   end
143 end
sql() click to toggle source

Same as select_sql, not aliased directly to make subclassing simpler.

    # File lib/sequel/dataset/sql.rb
146 def sql
147   select_sql
148 end
truncate_sql() click to toggle source

Returns a TRUNCATE SQL query string. See truncate

DB[:items].truncate_sql # => 'TRUNCATE items'
    # File lib/sequel/dataset/sql.rb
153 def truncate_sql
154   if opts[:sql]
155     static_sql(opts[:sql])
156   else
157     check_truncation_allowed!
158     check_not_limited!(:truncate)
159     raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
160     t = String.new
161     source_list_append(t, opts[:from])
162     _truncate_sql(t)
163   end
164 end
update_sql(values = OPTS) click to toggle source

Formats an UPDATE statement using the given values. See update.

DB[:items].update_sql(price: 100, category: 'software')
# => "UPDATE items SET price = 100, category = 'software'

Raises an Error if the dataset is grouped or includes more than one table.

    # File lib/sequel/dataset/sql.rb
173 def update_sql(values = OPTS)
174   return static_sql(opts[:sql]) if opts[:sql]
175   check_modification_allowed!
176   check_not_limited!(:update)
177 
178   case values
179   when LiteralString
180     # nothing
181   when String
182     raise Error, "plain string passed to Dataset#update is not supported, use Sequel.lit to use a literal string"
183   end
184 
185   clone(:values=>values).send(:_update_sql)
186 end

4 - Methods that describe what the dataset supports

↑ top

Public Instance Methods

provides_accurate_rows_matched?() click to toggle source

Whether this dataset will provide accurate number of rows matched for delete and update statements, true by default. Accurate in this case is the number of rows matched by the dataset's filter.

   # File lib/sequel/dataset/features.rb
19 def provides_accurate_rows_matched?
20   true
21 end
quote_identifiers?() click to toggle source

Whether this dataset quotes identifiers.

   # File lib/sequel/dataset/features.rb
12 def quote_identifiers?
13   @opts.fetch(:quote_identifiers, true)
14 end
recursive_cte_requires_column_aliases?() click to toggle source

Whether you must use a column alias list for recursive CTEs, false by default.

   # File lib/sequel/dataset/features.rb
24 def recursive_cte_requires_column_aliases?
25   false
26 end
requires_placeholder_type_specifiers?() click to toggle source

Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer), false by default.

   # File lib/sequel/dataset/features.rb
36 def requires_placeholder_type_specifiers?
37   false
38 end
requires_sql_standard_datetimes?() click to toggle source

Whether the dataset requires SQL standard datetimes. False by default, as most allow strings with ISO 8601 format.

   # File lib/sequel/dataset/features.rb
30 def requires_sql_standard_datetimes?
31   false
32 end
supports_cte?(type=:select) click to toggle source

Whether the dataset supports common table expressions, false by default. If given, type can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.

   # File lib/sequel/dataset/features.rb
43 def supports_cte?(type=:select)
44   false
45 end
supports_cte_in_subqueries?() click to toggle source

Whether the dataset supports common table expressions in subqueries, false by default. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.

   # File lib/sequel/dataset/features.rb
50 def supports_cte_in_subqueries?
51   false
52 end
supports_derived_column_lists?() click to toggle source

Whether the database supports derived column lists (e.g. “table_expr AS table_alias(column_alias1, column_alias2, …)”), true by default.

   # File lib/sequel/dataset/features.rb
57 def supports_derived_column_lists?
58   true
59 end
supports_distinct_on?() click to toggle source

Whether the dataset supports or can emulate the DISTINCT ON clause, false by default.

   # File lib/sequel/dataset/features.rb
62 def supports_distinct_on?
63   false
64 end
supports_group_cube?() click to toggle source

Whether the dataset supports CUBE with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
67 def supports_group_cube?
68   false
69 end
supports_group_rollup?() click to toggle source

Whether the dataset supports ROLLUP with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
72 def supports_group_rollup?
73   false
74 end
supports_grouping_sets?() click to toggle source

Whether the dataset supports GROUPING SETS with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
77 def supports_grouping_sets?
78   false
79 end
supports_insert_select?() click to toggle source

Whether this dataset supports the insert_select method for returning all columns values directly from an insert query, false by default.

   # File lib/sequel/dataset/features.rb
83 def supports_insert_select?
84   supports_returning?(:insert)
85 end
supports_intersect_except?() click to toggle source

Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.

   # File lib/sequel/dataset/features.rb
88 def supports_intersect_except?
89   true
90 end
supports_intersect_except_all?() click to toggle source

Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.

   # File lib/sequel/dataset/features.rb
93 def supports_intersect_except_all?
94   true
95 end
supports_is_true?() click to toggle source

Whether the dataset supports the IS TRUE syntax, true by default.

    # File lib/sequel/dataset/features.rb
 98 def supports_is_true?
 99   true
100 end
supports_join_using?() click to toggle source

Whether the dataset supports the JOIN table USING (column1, …) syntax, true by default. If false, support is emulated using JOIN table ON (table.column1 = other_table.column1).

    # File lib/sequel/dataset/features.rb
104 def supports_join_using?
105   true
106 end
supports_lateral_subqueries?() click to toggle source

Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses, false by default.

    # File lib/sequel/dataset/features.rb
109 def supports_lateral_subqueries?
110   false
111 end
supports_limits_in_correlated_subqueries?() click to toggle source

Whether limits are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
114 def supports_limits_in_correlated_subqueries?
115   true
116 end
supports_modifying_joins?() click to toggle source

Whether modifying joined datasets is supported, false by default.

    # File lib/sequel/dataset/features.rb
124 def supports_modifying_joins?
125   false
126 end
supports_multiple_column_in?() click to toggle source

Whether the IN/NOT IN operators support multiple columns when an array of values is given, true by default.

    # File lib/sequel/dataset/features.rb
130 def supports_multiple_column_in?
131   true
132 end
supports_nowait?() click to toggle source

Whether the dataset supports skipping raising an error instead of waiting for locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
119 def supports_nowait?
120   false
121 end
supports_offsets_in_correlated_subqueries?() click to toggle source

Whether offsets are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
135 def supports_offsets_in_correlated_subqueries?
136   true
137 end
supports_ordered_distinct_on?() click to toggle source

Whether the dataset supports or can fully emulate the DISTINCT ON clause, including respecting the ORDER BY clause, false by default.

    # File lib/sequel/dataset/features.rb
141 def supports_ordered_distinct_on?
142   supports_distinct_on?
143 end
supports_regexp?() click to toggle source

Whether the dataset supports pattern matching by regular expressions, false by default.

    # File lib/sequel/dataset/features.rb
146 def supports_regexp?
147   false
148 end
supports_replace?() click to toggle source

Whether the dataset supports REPLACE syntax, false by default.

    # File lib/sequel/dataset/features.rb
151 def supports_replace?
152   false
153 end
supports_returning?(type) click to toggle source

Whether the RETURNING clause is supported for the given type of query, false by default. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
157 def supports_returning?(type)
158   false
159 end
supports_select_all_and_column?() click to toggle source

Whether the database supports SELECT *, column FROM table, true by default.

    # File lib/sequel/dataset/features.rb
167 def supports_select_all_and_column?
168   true
169 end
supports_skip_locked?() click to toggle source

Whether the dataset supports skipping locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
162 def supports_skip_locked?
163   false
164 end
supports_timestamp_timezones?() click to toggle source

Whether the dataset supports timezones in literal timestamps, false by default.

    # File lib/sequel/dataset/features.rb
172 def supports_timestamp_timezones?
173   false
174 end
supports_timestamp_usecs?() click to toggle source

Whether the dataset supports fractional seconds in literal timestamps, true by default.

    # File lib/sequel/dataset/features.rb
177 def supports_timestamp_usecs?
178   true
179 end
supports_where_true?() click to toggle source

Whether the dataset supports WHERE TRUE (or WHERE 1 for databases that that use 1 for true), true by default.

    # File lib/sequel/dataset/features.rb
188 def supports_where_true?
189   true
190 end
supports_window_functions?() click to toggle source

Whether the dataset supports window functions, false by default.

    # File lib/sequel/dataset/features.rb
182 def supports_window_functions?
183   false
184 end

Private Instance Methods

insert_supports_empty_values?() click to toggle source

Whether insert(nil) or insert({}) must be emulated by using at least one value.

    # File lib/sequel/dataset/features.rb
196 def insert_supports_empty_values?
197   true
198 end
requires_like_escape?() click to toggle source

Whether the dataset needs ESCAPE for LIKE for correct behavior.

    # File lib/sequel/dataset/features.rb
201 def requires_like_escape?
202   true
203 end
supports_cte_in_compounds?() click to toggle source

Whether common table expressions are supported in UNION/INTERSECT/EXCEPT clauses.

    # File lib/sequel/dataset/features.rb
206 def supports_cte_in_compounds?
207   supports_cte_in_subqueries?
208 end
supports_quoted_function_names?() click to toggle source

Whether the database supports quoting function names.

    # File lib/sequel/dataset/features.rb
211 def supports_quoted_function_names?
212   false
213 end
uses_returning?(type) click to toggle source

Whether the RETURNING clause is used for the given dataset. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
217 def uses_returning?(type)
218   opts[:returning] && !@opts[:sql] && supports_returning?(type)
219 end
uses_with_rollup?() click to toggle source

Whether the dataset uses WITH ROLLUP/CUBE instead of ROLLUP()/CUBE().

    # File lib/sequel/dataset/features.rb
222 def uses_with_rollup?
223   false
224 end

5 - Methods related to dataset graphing

↑ top

Public Instance Methods

add_graph_aliases(graph_aliases) click to toggle source

Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list (the equivalent of select_append when graphing). See set_graph_aliases.

DB[:table].add_graph_aliases(some_alias: [:table, :column])
# SELECT ..., table.column AS some_alias
   # File lib/sequel/dataset/graph.rb
18 def add_graph_aliases(graph_aliases)
19   graph = opts[:graph]
20   unless (graph && (ga = graph[:column_aliases]))
21     raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases"
22   end
23   columns, graph_aliases = graph_alias_columns(graph_aliases)
24   select_append(*columns).clone(:graph => Hash[graph].merge!(:column_aliases=>Hash[ga].merge!(graph_aliases).freeze).freeze)
25 end
graph(dataset, join_conditions = nil, options = OPTS, &block) click to toggle source

Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.

Arguments:

dataset

Can be a symbol (specifying a table), another dataset, or an SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

join_conditions

Any condition(s) allowed by join_table.

block

A block that is passed to join_table.

Options:

:from_self_alias

The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use.

:implicit_qualifier

The qualifier of implicit conditions, see join_table.

:join_only

Only join the tables, do not change the selected columns.

:join_type

The type of join to use (passed to join_table). Defaults to :left_outer.

:qualify

The type of qualification to do, see join_table.

:select

An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use graph instead of join_table.

:table_alias

The alias to use for the table. If not specified, doesn't alias the table. You will get an error if the alias (or table) name is used more than once.

    # File lib/sequel/dataset/graph.rb
 53 def graph(dataset, join_conditions = nil, options = OPTS, &block)
 54   # Allow the use of a dataset or symbol as the first argument
 55   # Find the table name/dataset based on the argument
 56   table_alias = options[:table_alias]
 57   table = dataset
 58   create_dataset = true
 59 
 60   case dataset
 61   when Symbol
 62     # let alias be the same as the table name (sans any optional schema)
 63     # unless alias explicitly given in the symbol using ___ notation and symbol splitting is enabled
 64     table_alias ||= split_symbol(table).compact.last
 65   when Dataset
 66     if dataset.simple_select_all?
 67       table = dataset.opts[:from].first
 68       table_alias ||= table
 69     else
 70       table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
 71     end
 72     create_dataset = false
 73   when SQL::Identifier
 74     table_alias ||= table.value
 75   when SQL::QualifiedIdentifier
 76     table_alias ||= split_qualifiers(table).last
 77   when SQL::AliasedExpression
 78     return graph(table.expression, join_conditions, {:table_alias=>table.alias}.merge!(options), &block)
 79   else
 80     raise Error, "The dataset argument should be a symbol or dataset"
 81   end
 82   table_alias = table_alias.to_sym
 83 
 84   if create_dataset
 85     dataset = db.from(table)
 86   end
 87 
 88   # Raise Sequel::Error with explanation that the table alias has been used
 89   raise_alias_error = lambda do
 90     raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
 91       "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
 92   end
 93 
 94   # Only allow table aliases that haven't been used
 95   raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
 96   
 97   table_alias_qualifier = qualifier_from_alias_symbol(table_alias, table)
 98   implicit_qualifier = options[:implicit_qualifier]
 99   ds = self
100 
101   # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs)
102   if (@opts[:graph_from_self] != false && !@opts[:graph] && joined_dataset?)
103     from_selfed = true
104     implicit_qualifier = options[:from_self_alias] || first_source
105     ds = ds.from_self(:alias=>implicit_qualifier)
106   end
107   
108   # Join the table early in order to avoid cloning the dataset twice
109   ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias_qualifier, :implicit_qualifier=>implicit_qualifier, :qualify=>options[:qualify], &block)
110 
111   return ds if options[:join_only]
112 
113   opts = ds.opts
114 
115   # Whether to include the table in the result set
116   add_table = options[:select] == false ? false : true
117 
118   if graph = opts[:graph]
119     graph = graph.dup
120     select = opts[:select].dup
121     [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
122   else
123     # Setup the initial graph data structure if it doesn't exist
124     qualifier = ds.first_source_alias
125     master = alias_symbol(qualifier)
126     raise_alias_error.call if master == table_alias
127 
128     # Master hash storing all .graph related information
129     graph = {}
130 
131     # Associates column aliases back to tables and columns
132     column_aliases = graph[:column_aliases] = {}
133 
134     # Associates table alias (the master is never aliased)
135     table_aliases = graph[:table_aliases] = {master=>self}
136 
137     # Keep track of the alias numbers used
138     ca_num = graph[:column_alias_num] = Hash.new(0)
139 
140     # All columns in the master table are never
141     # aliased, but are not included if set_graph_aliases
142     # has been used.
143     if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll)))
144       select = select.map do |sel|
145         raise Error, "can't figure out alias to use for graphing for #{sel.inspect}" unless column = _hash_key_symbol(sel)
146         column_aliases[column] = [master, column]
147         if from_selfed
148           # Initial dataset was wrapped in subselect, selected all
149           # columns in the subselect, qualified by the subselect alias.
150           Sequel.qualify(qualifier, Sequel.identifier(column))
151         else
152           # Initial dataset not wrapped in subslect, just make
153           # sure columns are qualified in some way.
154           qualified_expression(sel, qualifier)
155         end
156       end
157     else
158       select = columns.map do |column|
159         column_aliases[column] = [master, column]
160         SQL::QualifiedIdentifier.new(qualifier, column)
161       end
162     end
163   end
164 
165   # Add the table alias to the list of aliases
166   # Even if it isn't been used in the result set,
167   # we add a key for it with a nil value so we can check if it
168   # is used more than once
169   table_aliases = graph[:table_aliases]
170   table_aliases[table_alias] = add_table ? dataset : nil
171 
172   # Add the columns to the selection unless we are ignoring them
173   if add_table
174     column_aliases = graph[:column_aliases]
175     ca_num = graph[:column_alias_num]
176     # Which columns to add to the result set
177     cols = options[:select] || dataset.columns
178     # If the column hasn't been used yet, don't alias it.
179     # If it has been used, try table_column.
180     # If that has been used, try table_column_N
181     # using the next value of N that we know hasn't been
182     # used
183     cols.each do |column|
184       col_alias, identifier = if column_aliases[column]
185         column_alias = :"#{table_alias}_#{column}"
186         if column_aliases[column_alias]
187           column_alias_num = ca_num[column_alias]
188           column_alias = :"#{column_alias}_#{column_alias_num}" 
189           ca_num[column_alias] += 1
190         end
191         [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)]
192       else
193         ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column)
194         [column, ident]
195       end
196       column_aliases[col_alias] = [table_alias, column].freeze
197       select.push(identifier)
198     end
199   end
200   [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k].freeze}
201   ds = ds.clone(:graph=>graph.freeze)
202   ds.select(*select)
203 end
set_graph_aliases(graph_aliases) click to toggle source

This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of select for a graphed dataset, and must be used instead of select whenever graphing is used.

graph_aliases should be a hash with keys being symbols of column aliases, and values being either symbols or arrays with one to three elements. If the value is a symbol, it is assumed to be the same as a one element array containing that symbol. The first element of the array should be the table alias symbol. The second should be the actual column name symbol. If the array only has a single element the column name symbol will be assumed to be the same as the corresponding hash key. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.

DB[:artists].graph(:albums, :artist_id: :id).
  set_graph_aliases(name: :artists,
                    album_name: [:albums, :name],
                    forty_two: [:albums, :fourtwo, 42]).first
# SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
    # File lib/sequel/dataset/graph.rb
228 def set_graph_aliases(graph_aliases)
229   columns, graph_aliases = graph_alias_columns(graph_aliases)
230   if graph = opts[:graph]
231     select(*columns).clone(:graph => Hash[graph].merge!(:column_aliases=>graph_aliases.freeze).freeze)
232   else
233     raise Error, "cannot call #set_graph_aliases on an ungraphed dataset"
234   end
235 end
ungraphed() click to toggle source

Remove the splitting of results into subhashes, and all metadata related to the current graph (if any).

    # File lib/sequel/dataset/graph.rb
239 def ungraphed
240   clone(:graph=>nil)
241 end

Private Instance Methods

graph_alias_columns(graph_aliases) click to toggle source

Transform the hash of graph aliases and return a two element array where the first element is an array of identifiers suitable to pass to a select method, and the second is a new hash of preprocessed graph aliases.

    # File lib/sequel/dataset/graph.rb
267 def graph_alias_columns(graph_aliases)
268   gas = {}
269   identifiers = graph_aliases.map do |col_alias, tc| 
270     table, column, value = Array(tc)
271     column ||= col_alias
272     gas[col_alias] = [table, column].freeze
273     identifier = value || SQL::QualifiedIdentifier.new(table, column)
274     identifier = SQL::AliasedExpression.new(identifier, col_alias) if value || column != col_alias
275     identifier
276   end
277   [identifiers, gas]
278 end
qualifier_from_alias_symbol(aliaz, identifier) click to toggle source

Wrap the alias symbol in an SQL::Identifier if the identifier on which is based is an SQL::Identifier. This works around cases where symbol splitting is enabled and the alias symbol contains double embedded underscores which would be considered an implicit qualified identifier if not wrapped in an SQL::Identifier.

    # File lib/sequel/dataset/graph.rb
249 def qualifier_from_alias_symbol(aliaz, identifier)
250   case identifier
251   when SQL::QualifiedIdentifier
252     if identifier.column.is_a?(String)
253       Sequel.identifier(aliaz)
254     else
255       aliaz
256     end
257   when SQL::Identifier
258     Sequel.identifier(aliaz)
259   else
260     aliaz
261   end
262 end

6 - Miscellaneous methods

↑ top

Attributes

cache[R]

Access the cache for the current dataset. Should be used with caution, as access to the cache is not thread safe without a mutex if other threads can reference the dataset. Symbol keys prefixed with an underscore are reserved for internal use.

db[R]

The database related to this dataset. This is the Database instance that will execute all of this dataset's queries.

opts[R]

The hash of options for this dataset, keys are symbols.

Public Class Methods

new(db) click to toggle source

Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:

DB[:posts]

Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.

   # File lib/sequel/dataset/misc.rb
25 def initialize(db)
26   @db = db
27   @opts = OPTS
28   @cache = {}
29   freeze
30 end

Public Instance Methods

==(o) click to toggle source

Define a hash value such that datasets with the same class, DB, and opts will be considered equal.

   # File lib/sequel/dataset/misc.rb
34 def ==(o)
35   o.is_a?(self.class) && db == o.db && opts == o.opts
36 end
current_datetime() click to toggle source

An object representing the current date or time, should be an instance of Sequel.datetime_class.

   # File lib/sequel/dataset/misc.rb
40 def current_datetime
41   Sequel.datetime_class.now
42 end
dup() click to toggle source

Return self, as datasets are always frozen.

   # File lib/sequel/dataset/misc.rb
50 def dup
51   self
52 end
each_server() { |server(s)| ... } click to toggle source

Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:

DB[:configs].where(key: 'setting').each_server{|ds| ds.update(value: 'new_value')}
   # File lib/sequel/dataset/misc.rb
59 def each_server
60   db.servers.each{|s| yield server(s)}
61 end
eql?(o) click to toggle source

Alias for ==

   # File lib/sequel/dataset/misc.rb
45 def eql?(o)
46   self == o
47 end
escape_like(string) click to toggle source

Returns the string with the LIKE metacharacters (% and _) escaped. Useful for when the LIKE term is a user-provided string where metacharacters should not be recognized. Example:

ds.escape_like("foo\\%_") # 'foo\\\%\_'
   # File lib/sequel/dataset/misc.rb
68 def escape_like(string)
69   string.gsub(/[\\%_]/){|m| "\\#{m}"}
70 end
first_source() click to toggle source

Alias of first_source_alias

   # File lib/sequel/dataset/misc.rb
91 def first_source
92   first_source_alias
93 end
first_source_alias() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn't have a table, raises an Error. If the table is aliased, returns the aliased name.

DB[:table].first_source_alias
# => :table

DB[Sequel[:table].as(:t)].first_source_alias
# => :t
    # File lib/sequel/dataset/misc.rb
103 def first_source_alias
104   source = @opts[:from]
105   if source.nil? || source.empty?
106     raise Error, 'No source specified for query'
107   end
108   case s = source.first
109   when SQL::AliasedExpression
110     s.alias
111   when Symbol
112     _, _, aliaz = split_symbol(s)
113     aliaz ? aliaz.to_sym : s
114   else
115     s
116   end
117 end
first_source_table() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn't have a table, raises an error. If the table is aliased, returns the original table, not the alias

DB[:table].first_source_table
# => :table

DB[Sequel[:table].as(:t)].first_source_table
# => :table
    # File lib/sequel/dataset/misc.rb
128 def first_source_table
129   source = @opts[:from]
130   if source.nil? || source.empty?
131     raise Error, 'No source specified for query'
132   end
133   case s = source.first
134   when SQL::AliasedExpression
135     s.expression
136   when Symbol
137     sch, table, aliaz = split_symbol(s)
138     aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
139   else
140     s
141   end
142 end
freeze() click to toggle source

Freeze the opts when freezing the dataset.

Calls superclass method
   # File lib/sequel/dataset/misc.rb
74 def freeze
75   @opts.freeze
76   super
77 end
hash() click to toggle source

Define a hash value such that datasets with the same class, DB, and opts, will have the same hash value.

    # File lib/sequel/dataset/misc.rb
146 def hash
147   [self.class, db, opts].hash
148 end
inspect() click to toggle source

Returns a string representation of the dataset including the class name and the corresponding SQL select statement.

    # File lib/sequel/dataset/misc.rb
152 def inspect
153   "#<#{visible_class_name}: #{sql.inspect}>"
154 end
joined_dataset?() click to toggle source

Whether this dataset is a joined dataset (multiple FROM tables or any JOINs).

    # File lib/sequel/dataset/misc.rb
157 def joined_dataset?
158  !!((opts[:from].is_a?(Array) && opts[:from].size > 1) || opts[:join])
159 end
row_number_column() click to toggle source

The alias to use for the row_number column, used when emulating OFFSET support and for eager limit strategies

    # File lib/sequel/dataset/misc.rb
163 def row_number_column
164   :x_sequel_row_number_x
165 end
row_proc() click to toggle source

The row_proc for this database, should be any object that responds to call with a single hash argument and returns the object you want each to return.

    # File lib/sequel/dataset/misc.rb
169 def row_proc
170   @opts[:row_proc]
171 end
split_alias(c) click to toggle source

Splits a possible implicit alias in c, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.

    # File lib/sequel/dataset/misc.rb
176 def split_alias(c)
177   case c
178   when Symbol
179     c_table, column, aliaz = split_symbol(c)
180     [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
181   when SQL::AliasedExpression
182     [c.expression, c.alias]
183   when SQL::JoinClause
184     [c.table, c.table_alias]
185   else
186     [c, nil]
187   end
188 end
unqualified_column_for(v) click to toggle source

This returns an SQL::Identifier or SQL::AliasedExpression containing an SQL identifier that represents the unqualified column for the given value. The given value should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression containing one of those. In other cases, this returns nil.

    # File lib/sequel/dataset/misc.rb
195 def unqualified_column_for(v)
196   unless v.is_a?(String)
197     _unqualified_column_for(v)
198   end
199 end
unused_table_alias(table_alias, used_aliases = []) click to toggle source

Creates a unique table alias that hasn't already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with “_N” if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.

You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.

DB[:table].unused_table_alias(:t)
# => :t

DB[:table].unused_table_alias(:table)
# => :table_0

DB[:table, :table_0].unused_table_alias(:table)
# => :table_1

DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2])
# => :table_3
    # File lib/sequel/dataset/misc.rb
223 def unused_table_alias(table_alias, used_aliases = [])
224   table_alias = alias_symbol(table_alias)
225   used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
226   used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
227   if used_aliases.include?(table_alias)
228     i = 0
229     while true
230       ta = :"#{table_alias}_#{i}"
231       return ta unless used_aliases.include?(ta)
232       i += 1 
233     end
234   else
235     table_alias
236   end
237 end
with_quote_identifiers(v) click to toggle source

Return a modified dataset with quote_identifiers set.

    # File lib/sequel/dataset/misc.rb
240 def with_quote_identifiers(v)
241   clone(:quote_identifiers=>v, :skip_symbol_cache=>true)
242 end

Protected Instance Methods

_columns() click to toggle source

The cached columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
271 def _columns
272   cache_get(:_columns)
273 end
cache_get(k) click to toggle source

Retreive a value from the dataset's cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
253 def cache_get(k)
254   Sequel.synchronize{@cache[k]}
255 end
cache_set(k, v) click to toggle source

Set a value in the dataset's cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
258 def cache_set(k, v)
259   Sequel.synchronize{@cache[k] = v}
260 end
clear_columns_cache() click to toggle source

Clear the columns hash for the current dataset. This is not a thread safe operation, so it should only be used if the dataset could not be used by another thread (such as one that was just created via clone).

    # File lib/sequel/dataset/misc.rb
266 def clear_columns_cache
267   @cache.delete(:_columns)
268 end

Private Instance Methods

_unqualified_column_for(v) click to toggle source

Internal recursive version of unqualified_column_for, handling Strings inside of other objects.

    # File lib/sequel/dataset/misc.rb
331 def _unqualified_column_for(v)
332   case v
333   when Symbol
334     _, c, a = Sequel.split_symbol(v)
335     c = Sequel.identifier(c)
336     a ? c.as(a) : c
337   when String
338     Sequel.identifier(v)
339   when SQL::Identifier
340     v
341   when SQL::QualifiedIdentifier
342     _unqualified_column_for(v.column)
343   when SQL::AliasedExpression
344     if expr = unqualified_column_for(v.expression)
345       SQL::AliasedExpression.new(expr, v.alias)
346     end
347   end
348 end
cached_dataset(key) { || ... } click to toggle source

Check the cache for the given key, returning the value. Otherwise, yield to get the dataset and cache the dataset under the given key.

    # File lib/sequel/dataset/misc.rb
279 def cached_dataset(key)
280   unless ds = cache_get(key)
281     ds = yield
282     cache_set(key, ds)
283   end
284 
285   ds
286 end
cached_placeholder_literalizer(key) { |pl| ... } click to toggle source

Return a cached placeholder literalizer for the given key if there is one for this dataset. If there isn't one, increment the counter for the number of calls for the key, and if the counter is at least three, then create a placeholder literalizer by yielding to the block, and cache it.

    # File lib/sequel/dataset/misc.rb
293 def cached_placeholder_literalizer(key)
294   if loader = cache_get(key)
295     return loader unless loader.is_a?(Integer)
296     loader += 1
297 
298     if loader >= 3
299       loader = Sequel::Dataset::PlaceholderLiteralizer.loader(self){|pl, _| yield pl}
300       cache_set(key, loader)
301     else
302       cache_set(key, loader + 1)
303       loader = nil
304     end
305   elsif cache_sql?
306     cache_set(key, 1)
307   end
308 
309   loader
310 end
columns=(v) click to toggle source

Set the columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
313 def columns=(v)
314   cache_set(:_columns, v)
315 end
initialize_clone(c)
Alias for: initialize_copy
initialize_copy(c) click to toggle source

Set the db, opts, and cache for the copy of the dataset.

    # File lib/sequel/dataset/misc.rb
318 def initialize_copy(c)
319   @db = c.db
320   @opts = Hash[c.opts]
321   if cols = c.cache_get(:_columns)
322     @cache = {:_columns=>cols}
323   else
324     @cache = {}
325   end
326 end
Also aliased as: initialize_clone
visible_class_name() click to toggle source

Return the class name for this dataset, but skip anonymous classes

    # File lib/sequel/dataset/misc.rb
351 def visible_class_name
352   c = self.class
353   c = c.superclass while c.name.nil? || c.name == ''
354   c.name
355 end

8 - Methods related to prepared statements or bound variables

↑ top

Constants

DEFAULT_PREPARED_STATEMENT_MODULE_METHODS
PREPARED_ARG_PLACEHOLDER
PREPARED_STATEMENT_MODULE_CODE

Private Class Methods

prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block) click to toggle source
   # File lib/sequel/dataset/prepared_statements.rb
20 def self.prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block)
21   code = PREPARED_STATEMENT_MODULE_CODE[code] || code
22 
23   Module.new do
24     Array(mods).each do |mod|
25       include mod
26     end
27 
28     if block
29       module_eval(&block)
30     end
31 
32     meths.each do |meth|
33       module_eval("def #{meth}(sql, opts=Sequel::OPTS) #{code}; super end", __FILE__, __LINE__)
34     end
35     private(*meths)
36   end
37 end

Public Instance Methods

bind(bind_vars=OPTS) click to toggle source

Set the bind variables to use for the call. If bind variables have already been set for this dataset, they are updated with the contents of bind_vars.

DB[:table].where(id: :$id).bind(id: 1).call(:first)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
275 def bind(bind_vars=OPTS)
276   bind_vars = if bv = @opts[:bind_vars]
277     Hash[bv].merge!(bind_vars).freeze
278   else
279     if bind_vars.frozen?
280       bind_vars
281     else
282       Hash[bind_vars]
283     end
284   end
285 
286   clone(:bind_vars=>bind_vars)
287 end
call(type, bind_variables=OPTS, *values, &block) click to toggle source

For the given type (:select, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.

DB[:table].where(id: :$id).call(:first, id: 1)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
296 def call(type, bind_variables=OPTS, *values, &block)
297   to_prepared_statement(type, values, :extend=>bound_variable_modules).call(bind_variables, &block)
298 end
prepare(type, name, *values) click to toggle source

Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement.

This returns a clone of the dataset extended with PreparedStatementMethods, which you can call with the hash of bind variables to use. The prepared statement is also stored in the associated Database, where it can be called by name. The following usage is identical:

ps = DB[:table].where(name: :$name).prepare(:first, :select_by_name)

ps.call(name: 'Blah')
# SELECT * FROM table WHERE name = ? -- ('Blah')
# => {:id=>1, :name=>'Blah'}

DB.call(:select_by_name, name: 'Blah') # Same thing
    # File lib/sequel/dataset/prepared_statements.rb
316 def prepare(type, name, *values)
317   ps = to_prepared_statement(type, values, :name=>name, :extend=>prepared_statement_modules, :no_delayed_evaluations=>true)
318   ps.prepared_sql
319   db.set_prepared_statement(name, ps)
320   ps
321 end

Protected Instance Methods

to_prepared_statement(type, values=nil, opts=OPTS) click to toggle source

Return a cloned copy of the current dataset extended with PreparedStatementMethods, setting the type and modify values.

    # File lib/sequel/dataset/prepared_statements.rb
327 def to_prepared_statement(type, values=nil, opts=OPTS)
328   mods = opts[:extend] || []
329   mods += [PreparedStatementMethods]
330 
331   bind.
332     clone(:prepared_statement_name=>opts[:name], :prepared_type=>type, :prepared_modify_values=>values, :orig_dataset=>self, :no_cache_sql=>true, :prepared_args=>@opts[:prepared_args]||[], :no_delayed_evaluations=>opts[:no_delayed_evaluations]).
333     with_extend(*mods)
334 end

Private Instance Methods

allow_preparing_prepared_statements?() click to toggle source

Don't allow preparing prepared statements by default.

    # File lib/sequel/dataset/prepared_statements.rb
339 def allow_preparing_prepared_statements?
340   false
341 end
bound_variable_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
343 def bound_variable_modules
344   prepared_statement_modules
345 end
prepared_arg_placeholder() click to toggle source

The argument placeholder. Most databases used unnumbered arguments with question marks, so that is the default.

    # File lib/sequel/dataset/prepared_statements.rb
353 def prepared_arg_placeholder
354   PREPARED_ARG_PLACEHOLDER
355 end
prepared_statement_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
347 def prepared_statement_modules
348   []
349 end

9 - Internal Methods relating to SQL Creation

↑ top

Constants

BITWISE_METHOD_MAP
COUNT_FROM_SELF_OPTS
COUNT_OF_ALL_AS_COUNT
DEFAULT
EXISTS
IS_LITERALS
IS_OPERATORS
LIKE_OPERATORS
N_ARITY_OPERATORS
QUALIFY_KEYS
REGEXP_OPERATORS
TWO_ARITY_OPERATORS
WILDCARD

Public Class Methods

clause_methods(type, clauses) click to toggle source

Given a type (e.g. select) and an array of clauses, return an array of methods to call to build the SQL string.

    # File lib/sequel/dataset/sql.rb
195 def self.clause_methods(type, clauses)
196   clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
197 end
def_sql_method(mod, type, clauses) click to toggle source

Define a dataset literalization method for the given type in the given module, using the given clauses.

Arguments:

mod

Module in which to define method

type

Type of SQL literalization method to create, either :select, :insert, :update, or :delete

clauses

array of clauses that make up the SQL query for the type. This can either be a single array of symbols/strings, or it can be an array of pairs, with the first element in each pair being an if/elsif/else code fragment, and the second element in each pair being an array of symbol/strings for the appropriate branch.

    # File lib/sequel/dataset/sql.rb
209 def self.def_sql_method(mod, type, clauses)
210   priv = type == :update || type == :insert
211   cacheable = type == :select || type == :delete
212 
213   lines = []
214   lines << 'private' if priv
215   lines << "def #{'_' if priv}#{type}_sql"
216   lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
217   lines << "if sql = cache_get(:_#{type}_sql); return sql end" if cacheable
218   lines << 'check_modification_allowed!' << 'check_not_limited!(:delete)' if type == :delete
219   lines << 'sql = @opts[:append_sql] || sql_string_origin'
220 
221   if clauses.all?{|c| c.is_a?(Array)}
222     clauses.each do |i, cs|
223       lines << i
224       lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 
225     end 
226     lines << 'end'
227   else
228     lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
229   end
230 
231   lines << "cache_set(:_#{type}_sql, sql) if cache_sql?" if cacheable
232   lines << 'sql'
233   lines << 'end'
234 
235   mod.class_eval lines.join("\n"), __FILE__, __LINE__
236 end

Public Instance Methods

aliased_expression_sql_append(sql, ae) click to toggle source

Append literalization of aliased expression to SQL string.

    # File lib/sequel/dataset/sql.rb
270 def aliased_expression_sql_append(sql, ae)
271   literal_append(sql, ae.expression)
272   as_sql_append(sql, ae.alias, ae.columns)
273 end
array_sql_append(sql, a) click to toggle source

Append literalization of array to SQL string.

    # File lib/sequel/dataset/sql.rb
276 def array_sql_append(sql, a)
277   if a.empty?
278     sql << '(NULL)'
279   else
280     sql << '('
281     expression_list_append(sql, a)
282     sql << ')'
283   end
284 end
boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
287 def boolean_constant_sql_append(sql, constant)
288   if (constant == true || constant == false) && !supports_where_true?
289     sql << (constant == true ? '(1 = 1)' : '(1 = 0)')
290   else
291     literal_append(sql, constant)
292   end
293 end
case_expression_sql_append(sql, ce) click to toggle source

Append literalization of case expression to SQL string.

    # File lib/sequel/dataset/sql.rb
296 def case_expression_sql_append(sql, ce)
297   sql << '(CASE'
298   if ce.expression?
299     sql << ' '
300     literal_append(sql, ce.expression)
301   end
302   w = " WHEN "
303   t = " THEN "
304   ce.conditions.each do |c,r|
305     sql << w
306     literal_append(sql, c)
307     sql << t
308     literal_append(sql, r)
309   end
310   sql << " ELSE "
311   literal_append(sql, ce.default)
312   sql << " END)"
313 end
cast_sql_append(sql, expr, type) click to toggle source

Append literalization of cast expression to SQL string.

    # File lib/sequel/dataset/sql.rb
316 def cast_sql_append(sql, expr, type)
317   sql << 'CAST('
318   literal_append(sql, expr)
319   sql << ' AS ' << db.cast_type_literal(type).to_s
320   sql << ')'
321 end
column_all_sql_append(sql, ca) click to toggle source

Append literalization of column all selection to SQL string.

    # File lib/sequel/dataset/sql.rb
324 def column_all_sql_append(sql, ca)
325   qualified_identifier_sql_append(sql, ca.table, WILDCARD)
326 end
complex_expression_sql_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string.

    # File lib/sequel/dataset/sql.rb
329 def complex_expression_sql_append(sql, op, args)
330   case op
331   when *IS_OPERATORS
332     r = args[1]
333     if r.nil? || supports_is_true?
334       raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r]
335       sql << '('
336       literal_append(sql, args[0])
337       sql << ' ' << op.to_s << ' '
338       sql << val << ')'
339     elsif op == :IS
340       complex_expression_sql_append(sql, :"=", args)
341     else
342       complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args[0], nil)])
343     end
344   when :IN, :"NOT IN"
345     cols = args[0]
346     vals = args[1]
347     col_array = true if cols.is_a?(Array)
348     if vals.is_a?(Array)
349       val_array = true
350       empty_val_array = vals == []
351     end
352     if empty_val_array
353       literal_append(sql, empty_array_value(op, cols))
354     elsif col_array
355       if !supports_multiple_column_in?
356         if val_array
357           expr = SQL::BooleanExpression.new(:OR, *vals.to_a.map{|vs| SQL::BooleanExpression.from_value_pairs(cols.to_a.zip(vs).map{|c, v| [c, v]})})
358           literal_append(sql, op == :IN ? expr : ~expr)
359         else
360           old_vals = vals
361           vals = vals.naked if vals.is_a?(Sequel::Dataset)
362           vals = vals.to_a
363           val_cols = old_vals.columns
364           complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
365         end
366       else
367         # If the columns and values are both arrays, use array_sql instead of
368         # literal so that if values is an array of two element arrays, it
369         # will be treated as a value list instead of a condition specifier.
370         sql << '('
371         literal_append(sql, cols)
372         sql << ' ' << op.to_s << ' '
373         if val_array
374           array_sql_append(sql, vals)
375         else
376           literal_append(sql, vals)
377         end
378         sql << ')'
379       end
380     else
381       sql << '('
382       literal_append(sql, cols)
383       sql << ' ' << op.to_s << ' '
384       literal_append(sql, vals)
385       sql << ')'
386     end
387   when :LIKE, :'NOT LIKE'
388     sql << '('
389     literal_append(sql, args[0])
390     sql << ' ' << op.to_s << ' '
391     literal_append(sql, args[1])
392     if requires_like_escape?
393       sql << " ESCAPE "
394       literal_append(sql, "\\")
395     end
396     sql << ')'
397   when :ILIKE, :'NOT ILIKE'
398     complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
399   when :**
400     function_sql_append(sql, Sequel.function(:power, *args))
401   when *TWO_ARITY_OPERATORS
402     if REGEXP_OPERATORS.include?(op) && !supports_regexp?
403       raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
404     end
405     sql << '('
406     literal_append(sql, args[0])
407     sql << ' ' << op.to_s << ' '
408     literal_append(sql, args[1])
409     sql << ')'
410   when *N_ARITY_OPERATORS
411     sql << '('
412     c = false
413     op_str = " #{op} "
414     args.each do |a|
415       sql << op_str if c
416       literal_append(sql, a)
417       c ||= true
418     end
419     sql << ')'
420   when :NOT
421     sql << 'NOT '
422     literal_append(sql, args[0])
423   when :NOOP
424     literal_append(sql, args[0])
425   when :'B~'
426     sql << '~'
427     literal_append(sql, args[0])
428   when :extract
429     sql << 'extract(' << args[0].to_s << ' FROM '
430     literal_append(sql, args[1])
431     sql << ')'
432   else
433     raise(InvalidOperation, "invalid operator #{op}")
434   end
435 end
constant_sql_append(sql, constant) click to toggle source

Append literalization of constant to SQL string.

    # File lib/sequel/dataset/sql.rb
438 def constant_sql_append(sql, constant)
439   sql << constant.to_s
440 end
delayed_evaluation_sql_append(sql, delay) click to toggle source

Append literalization of delayed evaluation to SQL string, causing the delayed evaluation proc to be evaluated.

    # File lib/sequel/dataset/sql.rb
444 def delayed_evaluation_sql_append(sql, delay)
445   # Delayed evaluations are used specifically so the SQL
446   # can differ in subsequent calls, so we definitely don't
447   # want to cache the sql in this case.
448   disable_sql_caching!
449 
450   if recorder = @opts[:placeholder_literalizer]
451     recorder.use(sql, lambda{delay.call(self)}, nil)
452   else
453     literal_append(sql, delay.call(self))
454   end
455 end
function_sql_append(sql, f) click to toggle source

Append literalization of function call to SQL string.

    # File lib/sequel/dataset/sql.rb
458 def function_sql_append(sql, f)
459   name = f.name
460   opts = f.opts
461 
462   if opts[:emulate]
463     if emulate_function?(name)
464       emulate_function_sql_append(sql, f)
465       return
466     end
467 
468     name = native_function_name(name) 
469   end
470 
471   sql << 'LATERAL ' if opts[:lateral]
472 
473   case name
474   when SQL::Identifier
475     if supports_quoted_function_names? && opts[:quoted]
476       literal_append(sql, name)
477     else
478       sql << name.value.to_s
479     end
480   when SQL::QualifiedIdentifier
481     if supports_quoted_function_names? && opts[:quoted] != false
482       literal_append(sql, name)
483     else
484       sql << split_qualifiers(name).join('.')
485     end
486   else
487     if supports_quoted_function_names? && opts[:quoted]
488       quote_identifier_append(sql, name)
489     else
490       sql << name.to_s
491     end
492   end
493 
494   sql << '('
495   if opts[:*]
496     sql << '*'
497   else
498     sql << "DISTINCT " if opts[:distinct]
499     expression_list_append(sql, f.args)
500     if order = opts[:order]
501       sql << " ORDER BY "
502       expression_list_append(sql, order)
503     end
504   end
505   sql << ')'
506 
507   if group = opts[:within_group]
508     sql << " WITHIN GROUP (ORDER BY "
509     expression_list_append(sql, group)
510     sql << ')'
511   end
512 
513   if filter = opts[:filter]
514     sql << " FILTER (WHERE "
515     literal_append(sql, filter_expr(filter, &opts[:filter_block]))
516     sql << ')'
517   end
518 
519   if window = opts[:over]
520     sql << ' OVER '
521     window_sql_append(sql, window.opts)
522   end
523 
524   if opts[:with_ordinality]
525     sql << " WITH ORDINALITY"
526   end
527 end
join_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN clause without ON or USING to SQL string.

    # File lib/sequel/dataset/sql.rb
530 def join_clause_sql_append(sql, jc)
531   table = jc.table
532   table_alias = jc.table_alias
533   table_alias = nil if table == table_alias && !jc.column_aliases
534   sql << ' ' << join_type_sql(jc.join_type) << ' '
535   identifier_append(sql, table)
536   as_sql_append(sql, table_alias, jc.column_aliases) if table_alias
537 end
join_on_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN ON clause to SQL string.

    # File lib/sequel/dataset/sql.rb
540 def join_on_clause_sql_append(sql, jc)
541   join_clause_sql_append(sql, jc)
542   sql << ' ON '
543   literal_append(sql, filter_expr(jc.on))
544 end
join_using_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN USING clause to SQL string.

    # File lib/sequel/dataset/sql.rb
547 def join_using_clause_sql_append(sql, jc)
548   join_clause_sql_append(sql, jc)
549   sql << ' USING ('
550   column_list_append(sql, jc.using)
551   sql << ')'
552 end
negative_boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of negative boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
555 def negative_boolean_constant_sql_append(sql, constant)
556   sql << 'NOT '
557   boolean_constant_sql_append(sql, constant)
558 end
ordered_expression_sql_append(sql, oe) click to toggle source

Append literalization of ordered expression to SQL string.

    # File lib/sequel/dataset/sql.rb
561 def ordered_expression_sql_append(sql, oe)
562   literal_append(sql, oe.expression)
563   sql << (oe.descending ? ' DESC' : ' ASC')
564   case oe.nulls
565   when :first
566     sql << " NULLS FIRST"
567   when :last
568     sql << " NULLS LAST"
569   end
570 end
placeholder_literal_string_sql_append(sql, pls) click to toggle source

Append literalization of placeholder literal string to SQL string.

    # File lib/sequel/dataset/sql.rb
573 def placeholder_literal_string_sql_append(sql, pls)
574   args = pls.args
575   str = pls.str
576   sql << '(' if pls.parens
577   if args.is_a?(Hash)
578     if args.empty?
579       sql << str
580     else
581       re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
582       while true
583         previous, q, str = str.partition(re)
584         sql << previous
585         literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
586         break if str.empty?
587       end
588     end
589   elsif str.is_a?(Array)
590     len = args.length
591     str.each_with_index do |s, i|
592       sql << s
593       literal_append(sql, args[i]) unless i == len
594     end
595     unless str.length == args.length || str.length == args.length + 1
596       raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
597     end
598   else
599     i = -1
600     match_len = args.length - 1
601     while true
602       previous, q, str = str.partition('?')
603       sql << previous
604       literal_append(sql, args.at(i+=1)) unless q.empty?
605       if str.empty?
606         unless i == match_len
607           raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder string"
608         end
609         break
610       end
611     end
612   end
613   sql << ')' if pls.parens
614 end
qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) click to toggle source

Append literalization of qualified identifier to SQL string. If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.

    # File lib/sequel/dataset/sql.rb
619 def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
620   identifier_append(sql, table)
621   sql << '.'
622   identifier_append(sql, column)
623 end
quote_identifier_append(sql, name) click to toggle source

Append literalization of unqualified identifier to SQL string. Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.

    # File lib/sequel/dataset/sql.rb
629 def quote_identifier_append(sql, name)
630   if name.is_a?(LiteralString)
631     sql << name
632   else
633     name = name.value if name.is_a?(SQL::Identifier)
634     name = input_identifier(name)
635     if quote_identifiers?
636       quoted_identifier_append(sql, name)
637     else
638       sql << name
639     end
640   end
641 end
quote_schema_table_append(sql, table) click to toggle source

Append literalization of identifier or unqualified identifier to SQL string.

    # File lib/sequel/dataset/sql.rb
644 def quote_schema_table_append(sql, table)
645   schema, table = schema_and_table(table)
646   if schema
647     quote_identifier_append(sql, schema)
648     sql << '.'
649   end
650   quote_identifier_append(sql, table)
651 end
quoted_identifier_append(sql, name) click to toggle source

Append literalization of quoted identifier to SQL string. This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).

    # File lib/sequel/dataset/sql.rb
657 def quoted_identifier_append(sql, name)
658   sql << '"' << name.to_s.gsub('"', '""') << '"'
659 end
schema_and_table(table_name, sch=nil) click to toggle source

Split the schema information from the table, returning two strings, one for the schema and one for the table. The returned schema may be nil, but the table will always have a string value.

Note that this function does not handle tables with more than one level of qualification (e.g. database.schema.table on Microsoft SQL Server).

    # File lib/sequel/dataset/sql.rb
668 def schema_and_table(table_name, sch=nil)
669   sch = sch.to_s if sch
670   case table_name
671   when Symbol
672     s, t, _ = split_symbol(table_name)
673     [s||sch, t]
674   when SQL::QualifiedIdentifier
675     [table_name.table.to_s, table_name.column.to_s]
676   when SQL::Identifier
677     [sch, table_name.value.to_s]
678   when String
679     [sch, table_name]
680   else
681     raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
682   end
683 end
split_qualifiers(table_name, *args) click to toggle source

Splits table_name into an array of strings.

ds.split_qualifiers(:s) # ['s']
ds.split_qualifiers(Sequel[:t][:s]) # ['t', 's']
ds.split_qualifiers(Sequel[:d][:t][:s]) # ['d', 't', 's']
ds.split_qualifiers(Sequel.qualify(Sequel[:h][:d], Sequel[:t][:s])) # ['h', 'd', 't', 's']
    # File lib/sequel/dataset/sql.rb
691 def split_qualifiers(table_name, *args)
692   case table_name
693   when SQL::QualifiedIdentifier
694     split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
695   else
696     sch, table = schema_and_table(table_name, *args)
697     sch ? [sch, table] : [table]
698   end
699 end
subscript_sql_append(sql, s) click to toggle source

Append literalization of subscripts (SQL array accesses) to SQL string.

    # File lib/sequel/dataset/sql.rb
702 def subscript_sql_append(sql, s)
703   literal_append(sql, s.expression)
704   sql << '['
705   sub = s.sub
706   if sub.length == 1 && (range = sub.first).is_a?(Range)
707     literal_append(sql, range.begin)
708     sql << ':'
709     e = range.end
710     e -= 1 if range.exclude_end? && e.is_a?(Integer)
711     literal_append(sql, e)
712   else
713     expression_list_append(sql, s.sub)
714   end
715   sql << ']'
716 end
window_sql_append(sql, opts) click to toggle source

Append literalization of windows (for window functions) to SQL string.

    # File lib/sequel/dataset/sql.rb
719 def window_sql_append(sql, opts)
720   raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
721   sql << '('
722   window, part, order, frame = opts.values_at(:window, :partition, :order, :frame)
723   space = false
724   space_s = ' '
725   if window
726     literal_append(sql, window)
727     space = true
728   end
729   if part
730     sql << space_s if space
731     sql << "PARTITION BY "
732     expression_list_append(sql, Array(part))
733     space = true
734   end
735   if order
736     sql << space_s if space
737     sql << "ORDER BY "
738     expression_list_append(sql, Array(order))
739     space = true
740   end
741   case frame
742     when nil
743       # nothing
744     when :all
745       sql << space_s if space
746       sql << "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING"
747     when :rows
748       sql << space_s if space
749       sql << "ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW"
750     when String
751       sql << space_s if space
752       sql << frame
753     else
754       raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil"
755   end
756   sql << ')'
757 end

Protected Instance Methods

compound_from_self() click to toggle source

Return a from_self dataset if an order or limit is specified, so it works as expected with UNION, EXCEPT, and INTERSECT clauses.

    # File lib/sequel/dataset/sql.rb
763 def compound_from_self
764   (@opts[:sql] || @opts[:limit] || @opts[:order] || @opts[:offset]) ? from_self : self
765 end

Private Instance Methods

_truncate_sql(table) click to toggle source

Formats the truncate statement. Assumes the table given has already been literalized.

    # File lib/sequel/dataset/sql.rb
771 def _truncate_sql(table)
772   "TRUNCATE TABLE #{table}"
773 end
aggregate_dataset() click to toggle source

Clone of this dataset usable in aggregate operations. Does a from_self if dataset contains any parameters that would affect normal aggregation, or just removes an existing order if not.

    # File lib/sequel/dataset/sql.rb
814 def aggregate_dataset
815   options_overlap(COUNT_FROM_SELF_OPTS) ? from_self : unordered
816 end
alias_alias_symbol(s) click to toggle source

Returns an appropriate symbol for the alias represented by s.

    # File lib/sequel/dataset/sql.rb
776 def alias_alias_symbol(s)
777   case s
778   when Symbol
779     s
780   when String
781     s.to_sym
782   when SQL::Identifier
783     s.value.to_s.to_sym
784   else
785     raise Error, "Invalid alias for alias_alias_symbol: #{s.inspect}"
786   end
787 end
alias_symbol(sym) click to toggle source

Returns an appropriate alias symbol for the given object, which can be a Symbol, String, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

    # File lib/sequel/dataset/sql.rb
792 def alias_symbol(sym)
793   case sym
794   when Symbol
795     s, t, a = split_symbol(sym)
796     a || s ? (a || t).to_sym : sym
797   when String
798     sym.to_sym
799   when SQL::Identifier
800     sym.value.to_s.to_sym
801   when SQL::QualifiedIdentifier
802     alias_symbol(sym.column)
803   when SQL::AliasedExpression
804     alias_alias_symbol(sym.alias)
805   else
806     raise Error, "Invalid alias for alias_symbol: #{sym.inspect}"
807   end
808 end
as_sql_append(sql, aliaz, column_aliases=nil) click to toggle source

Append aliasing expression to SQL string.

    # File lib/sequel/dataset/sql.rb
819 def as_sql_append(sql, aliaz, column_aliases=nil)
820   sql << ' AS '
821   quote_identifier_append(sql, aliaz)
822   if column_aliases
823     raise Error, "#{db.database_type} does not support derived column lists" unless supports_derived_column_lists?
824     sql << '('
825     identifier_list_append(sql, column_aliases)
826     sql << ')'
827   end
828 end
cache_sql?() click to toggle source

Don't allow caching SQL if specifically marked not to.

    # File lib/sequel/dataset/sql.rb
831 def cache_sql?
832   !@opts[:no_cache_sql] && !cache_get(:_no_cache_sql)
833 end
check_modification_allowed!() click to toggle source

Raise an InvalidOperation exception if deletion is not allowed for this dataset.

    # File lib/sequel/dataset/sql.rb
836 def check_modification_allowed!
837   raise(InvalidOperation, "Grouped datasets cannot be modified") if opts[:group]
838   raise(InvalidOperation, "Joined datasets cannot be modified") if !supports_modifying_joins? && joined_dataset?
839 end
check_not_limited!(type) click to toggle source

Raise error if the dataset uses limits or offsets.

    # File lib/sequel/dataset/sql.rb
842 def check_not_limited!(type)
843   return if @opts[:skip_limit_check] && type != :truncate
844   raise InvalidOperation, "Dataset##{type} not supported on datasets with limits or offsets" if opts[:limit] || opts[:offset]
845 end
check_truncation_allowed!() click to toggle source

Alias of check_modification_allowed!

    # File lib/sequel/dataset/sql.rb
848 def check_truncation_allowed!
849   check_modification_allowed!
850 end
column_list_append(sql, columns) click to toggle source

Append column list to SQL string. If the column list is empty, a wildcard (*) is appended.

    # File lib/sequel/dataset/sql.rb
854 def column_list_append(sql, columns)
855   if (columns.nil? || columns.empty?)
856     sql << '*'
857   else
858     expression_list_append(sql, columns)
859   end
860 end
complex_expression_arg_pairs(args) { |args, args| ... } click to toggle source

Yield each pair of arguments to the block, which should return an object representing the SQL expression for those two arguments. For more than two arguments, the first argument to the block will be result of the previous block call.

    # File lib/sequel/dataset/sql.rb
866 def complex_expression_arg_pairs(args)
867   case args.length
868   when 1
869     args[0]
870   when 2
871     yield args[0], args[1]
872   else
873     args.inject{|m, a| yield(m, a)}
874   end
875 end
complex_expression_arg_pairs_append(sql, args, &block) click to toggle source

Append the literalization of the args using complex_expression_arg_pairs to the given SQL string, used when database operator/function is 2-ary where Sequel expression is N-ary.

    # File lib/sequel/dataset/sql.rb
880 def complex_expression_arg_pairs_append(sql, args, &block)
881   literal_append(sql, complex_expression_arg_pairs(args, &block))
882 end
complex_expression_emulate_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string, for operators unsupported by some databases. Used by adapters for databases that don't support the operators natively.

    # File lib/sequel/dataset/sql.rb
887 def complex_expression_emulate_append(sql, op, args)
888   case op
889   when :%
890     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(:MOD, a, b)}
891   when :>>
892     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel./(a, Sequel.function(:power, 2, b))}
893   when :<<
894     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.*(a, Sequel.function(:power, 2, b))}
895   when :&, :|, :^
896     f = BITWISE_METHOD_MAP[op]
897     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(f, a, b)}
898   when :'B~'
899     sql << "((0 - "
900     literal_append(sql, args[0])
901     sql << ") - 1)"
902   end
903 end
compound_dataset_sql_append(sql, ds) click to toggle source

Append literalization of dataset used in UNION/INTERSECT/EXCEPT clause to SQL string.

    # File lib/sequel/dataset/sql.rb
906 def compound_dataset_sql_append(sql, ds)
907   subselect_sql_append(sql, ds)
908 end
dataset_alias(number) click to toggle source

The alias to use for datasets, takes a number to make sure the name is unique.

    # File lib/sequel/dataset/sql.rb
911 def dataset_alias(number)
912   :"t#{number}"
913 end
default_timestamp_format() click to toggle source

The strftime format to use when literalizing the time.

    # File lib/sequel/dataset/sql.rb
916 def default_timestamp_format
917   requires_sql_standard_datetimes? ? "TIMESTAMP '%Y-%m-%d %H:%M:%S%N%z'" : "'%Y-%m-%d %H:%M:%S%N%z'"
918 end
delete_delete_sql(sql) click to toggle source
    # File lib/sequel/dataset/sql.rb
920 def delete_delete_sql(sql)
921   sql << 'DELETE'
922 end
delete_from_sql(sql) click to toggle source
    # File lib/sequel/dataset/sql.rb
924 def delete_from_sql(sql)
925   if f = @opts[:from]
926     sql << ' FROM '
927     source_list_append(sql, f)
928   end
929 end
delete_order_sql(sql)
Alias for: select_order_sql
delete_returning_sql(sql)
delete_where_sql(sql)
Alias for: select_where_sql
delete_with_sql(sql)
Alias for: select_with_sql
disable_sql_caching!() click to toggle source

Disable caching of SQL for the current dataset

    # File lib/sequel/dataset/sql.rb
932 def disable_sql_caching!
933   cache_set(:_no_cache_sql, true)
934 end
empty_array_value(op, cols) click to toggle source

An expression for how to handle an empty array lookup.

    # File lib/sequel/dataset/sql.rb
976 def empty_array_value(op, cols)
977   {1 => ((op == :IN) ? 0 : 1)}
978 end
empty_from_sql() click to toggle source

An SQL FROM clause to use in SELECT statements where the dataset has no from tables.

    # File lib/sequel/dataset/sql.rb
938 def empty_from_sql
939   nil
940 end
emulate_function?(name) click to toggle source

Whether to emulate the function with the given name. This should only be true if the emulation goes beyond choosing a function with a different name.

    # File lib/sequel/dataset/sql.rb
944 def emulate_function?(name)
945   false
946 end
expression_list_append(sql, columns) click to toggle source

Append literalization of array of expressions to SQL string, separating them with commas.

    # File lib/sequel/dataset/sql.rb
950 def expression_list_append(sql, columns)
951   c = false
952   co = ', '
953   columns.each do |col|
954     sql << co if c
955     literal_append(sql, col)
956     c ||= true
957   end
958 end
format_timestamp(v) click to toggle source

Format the timestamp based on the default_timestamp_format, with a couple of modifiers. First, allow %N to be used for fractions seconds (if the database supports them), and override %z to always use a numeric offset of hours and minutes.

     # File lib/sequel/dataset/sql.rb
 984 def format_timestamp(v)
 985   v2 = db.from_application_timestamp(v)
 986   fmt = default_timestamp_format.gsub(/%[Nz]/) do |m|
 987     if m == '%N'
 988       # Ruby 1.9 supports %N in timestamp formats, but Sequel has supported %N
 989       # for longer in a different way, where the . is already appended and only 6
 990       # decimal places are used by default.
 991       format_timestamp_usec(v.is_a?(DateTime) ? v.sec_fraction*(1000000) : v.usec) if supports_timestamp_usecs?
 992     else
 993       if supports_timestamp_timezones?
 994         # Would like to just use %z format, but it doesn't appear to work on Windows
 995         # Instead, the offset fragment is constructed manually
 996         minutes = (v2.is_a?(DateTime) ? v2.offset * 1440 : v2.utc_offset/60).to_i
 997         format_timestamp_offset(*minutes.divmod(60))
 998       end
 999     end
1000   end
1001   v2.strftime(fmt)
1002 end
format_timestamp_offset(hour, minute) click to toggle source

Return the SQL timestamp fragment to use for the timezone offset.

     # File lib/sequel/dataset/sql.rb
1005 def format_timestamp_offset(hour, minute)
1006   sprintf("%+03i%02i", hour, minute)
1007 end
format_timestamp_usec(usec, ts=timestamp_precision) click to toggle source

Return the SQL timestamp fragment to use for the fractional time part. Should start with the decimal point. Uses 6 decimal places by default.

     # File lib/sequel/dataset/sql.rb
1011 def format_timestamp_usec(usec, ts=timestamp_precision)
1012   unless ts == 6
1013     usec = usec/(10 ** (6 - ts))
1014   end
1015   sprintf(".%0#{ts}d", usec)
1016 end
grouping_element_list_append(sql, columns) click to toggle source

Append literalization of array of grouping elements to SQL string, seperating them with commas.

    # File lib/sequel/dataset/sql.rb
961 def grouping_element_list_append(sql, columns)
962   c = false
963   co = ', '
964   columns.each do |col|
965     sql << co if c
966     if col.is_a?(Array) && col.empty?
967       sql << '()'
968     else
969       literal_append(sql, Array(col))
970     end
971     c ||= true
972   end
973 end
identifier_append(sql, v) click to toggle source

Append literalization of identifier to SQL string, considering regular strings as SQL identifiers instead of SQL strings.

     # File lib/sequel/dataset/sql.rb
1020 def identifier_append(sql, v)
1021   if v.is_a?(String)
1022     case v
1023     when LiteralString
1024       sql << v
1025     when SQL::Blob
1026       literal_append(sql, v)
1027     else
1028       quote_identifier_append(sql, v)
1029     end
1030   else
1031     literal_append(sql, v)
1032   end
1033 end
identifier_list_append(sql, args) click to toggle source

Append literalization of array of identifiers to SQL string.

     # File lib/sequel/dataset/sql.rb
1036 def identifier_list_append(sql, args)
1037   c = false
1038   comma = ', '
1039   args.each do |a|
1040     sql << comma if c
1041     identifier_append(sql, a)
1042     c ||= true
1043   end
1044 end
input_identifier(v) click to toggle source

Upcase identifiers by default when inputting them into the database.

     # File lib/sequel/dataset/sql.rb
1047 def input_identifier(v)
1048   v.to_s.upcase
1049 end
insert_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1060 def insert_columns_sql(sql)
1061   columns = opts[:columns]
1062   if columns && !columns.empty?
1063     sql << ' ('
1064     identifier_list_append(sql, columns)
1065     sql << ')'
1066   end 
1067 end
insert_empty_columns_values() click to toggle source

The columns and values to use for an empty insert if the database doesn't support INSERT with DEFAULT VALUES.

     # File lib/sequel/dataset/sql.rb
1071 def insert_empty_columns_values
1072   [[columns.last], [DEFAULT]]
1073 end
insert_insert_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1075 def insert_insert_sql(sql)
1076   sql << "INSERT"
1077 end
insert_into_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1051 def insert_into_sql(sql)
1052   sql << " INTO "
1053   if (f = @opts[:from]) && f.length == 1
1054     identifier_append(sql, unaliased_identifier(f.first))
1055   else
1056     source_list_append(sql, f)
1057   end
1058 end
insert_returning_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1098 def insert_returning_sql(sql)
1099   if opts.has_key?(:returning)
1100     sql << " RETURNING "
1101     column_list_append(sql, Array(opts[:returning]))
1102   end
1103 end
insert_values_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1079 def insert_values_sql(sql)
1080   case values = opts[:values]
1081   when Array
1082     if values.empty?
1083       sql << " DEFAULT VALUES"
1084     else
1085       sql << " VALUES "
1086       literal_append(sql, values)
1087     end
1088   when Dataset
1089     sql << ' '
1090     subselect_sql_append(sql, values)
1091   when LiteralString
1092     sql << ' ' << values
1093   else
1094     raise Error, "Unsupported INSERT values type, should be an Array or Dataset: #{values.inspect}"
1095   end
1096 end
insert_with_sql(sql)
Alias for: select_with_sql
join_type_sql(join_type) click to toggle source

SQL fragment specifying a JOIN type, converts underscores to spaces and upcases.

     # File lib/sequel/dataset/sql.rb
1109 def join_type_sql(join_type)
1110   "#{join_type.to_s.gsub('_', ' ').upcase} JOIN"
1111 end
literal_array_append(sql, v) click to toggle source

Append a literalization of the array to SQL string. Treats as an expression if an array of all two pairs, or as a SQL array otherwise.

     # File lib/sequel/dataset/sql.rb
1115 def literal_array_append(sql, v)
1116   if Sequel.condition_specifier?(v)
1117     literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1118   else
1119     array_sql_append(sql, v)
1120   end
1121 end
literal_big_decimal(v) click to toggle source

SQL fragment for BigDecimal

     # File lib/sequel/dataset/sql.rb
1124 def literal_big_decimal(v)
1125   d = v.to_s("F")
1126   v.nan? || v.infinite? ?  "'#{d}'" : d
1127 end
literal_blob_append(sql, v) click to toggle source

Append literalization of SQL::Blob to SQL string.

     # File lib/sequel/dataset/sql.rb
1130 def literal_blob_append(sql, v)
1131   literal_string_append(sql, v)
1132 end
literal_dataset_append(sql, v) click to toggle source

Append literalization of dataset to SQL string. Does a subselect inside parantheses.

     # File lib/sequel/dataset/sql.rb
1135 def literal_dataset_append(sql, v)
1136   sql << 'LATERAL ' if v.opts[:lateral]
1137   sql << '('
1138   subselect_sql_append(sql, v)
1139   sql << ')'
1140 end
literal_date(v) click to toggle source

SQL fragment for Date, using the ISO8601 format.

     # File lib/sequel/dataset/sql.rb
1143 def literal_date(v)
1144   if requires_sql_standard_datetimes?
1145     v.strftime("DATE '%Y-%m-%d'")
1146   else
1147     v.strftime("'%Y-%m-%d'")
1148   end
1149 end
literal_datetime(v) click to toggle source

SQL fragment for DateTime

     # File lib/sequel/dataset/sql.rb
1152 def literal_datetime(v)
1153   format_timestamp(v)
1154 end
literal_datetime_append(sql, v) click to toggle source

Append literalization of DateTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1157 def literal_datetime_append(sql, v)
1158   sql << literal_datetime(v)
1159 end
literal_expression_append(sql, v) click to toggle source

Append literalization of SQL::Expression to SQL string.

     # File lib/sequel/dataset/sql.rb
1162 def literal_expression_append(sql, v)
1163   v.to_s_append(self, sql)
1164 end
literal_false() click to toggle source

SQL fragment for false

     # File lib/sequel/dataset/sql.rb
1167 def literal_false
1168   "'f'"
1169 end
literal_float(v) click to toggle source

SQL fragment for Float

     # File lib/sequel/dataset/sql.rb
1172 def literal_float(v)
1173   v.to_s
1174 end
literal_hash_append(sql, v) click to toggle source

Append literalization of Hash to SQL string, treating hash as a boolean expression.

     # File lib/sequel/dataset/sql.rb
1177 def literal_hash_append(sql, v)
1178   literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1179 end
literal_integer(v) click to toggle source

SQL fragment for Integer

     # File lib/sequel/dataset/sql.rb
1182 def literal_integer(v)
1183   v.to_s
1184 end
literal_nil() click to toggle source

SQL fragment for nil

     # File lib/sequel/dataset/sql.rb
1187 def literal_nil
1188   "NULL"
1189 end
literal_other_append(sql, v) click to toggle source

Append a literalization of the object to the given SQL string. Calls sql_literal_append if object responds to it, otherwise calls sql_literal if object responds to it, otherwise raises an error. If a database specific type is allowed, this should be overriden in a subclass.

     # File lib/sequel/dataset/sql.rb
1195 def literal_other_append(sql, v)
1196   # We can't be sure if v will always literalize to the same SQL, so
1197   # don't cache SQL for a dataset that uses this.
1198   disable_sql_caching!
1199 
1200   if v.respond_to?(:sql_literal_append)
1201     v.sql_literal_append(self, sql)
1202   elsif v.respond_to?(:sql_literal)
1203     sql << v.sql_literal(self)
1204   else
1205     raise Error, "can't express #{v.inspect} as a SQL literal"
1206   end
1207 end
literal_sqltime(v) click to toggle source

SQL fragment for Sequel::SQLTime, containing just the time part

     # File lib/sequel/dataset/sql.rb
1210 def literal_sqltime(v)
1211   v.strftime("'%H:%M:%S#{format_timestamp_usec(v.usec, sqltime_precision) if supports_timestamp_usecs?}'")
1212 end
literal_sqltime_append(sql, v) click to toggle source

Append literalization of Sequel::SQLTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1215 def literal_sqltime_append(sql, v)
1216   sql << literal_sqltime(v)
1217 end
literal_string_append(sql, v) click to toggle source

Append literalization of string to SQL string.

     # File lib/sequel/dataset/sql.rb
1220 def literal_string_append(sql, v)
1221   sql << "'" << v.gsub("'", "''") << "'"
1222 end
literal_symbol_append(sql, v) click to toggle source

Append literalization of symbol to SQL string.

     # File lib/sequel/dataset/sql.rb
1225 def literal_symbol_append(sql, v)
1226   c_table, column, c_alias = split_symbol(v)
1227   if c_table
1228     quote_identifier_append(sql, c_table)
1229     sql << '.'
1230   end
1231   quote_identifier_append(sql, column)
1232   as_sql_append(sql, c_alias) if c_alias
1233 end
literal_time(v) click to toggle source

SQL fragment for Time

     # File lib/sequel/dataset/sql.rb
1236 def literal_time(v)
1237   format_timestamp(v)
1238 end
literal_time_append(sql, v) click to toggle source

Append literalization of Time to SQL string.

     # File lib/sequel/dataset/sql.rb
1241 def literal_time_append(sql, v)
1242   sql << literal_time(v)
1243 end
literal_true() click to toggle source

SQL fragment for true

     # File lib/sequel/dataset/sql.rb
1246 def literal_true
1247   "'t'"
1248 end
multi_insert_sql_strategy() click to toggle source

What strategy to use for import/multi_insert. While SQL-92 defaults to allowing multiple rows in a VALUES clause, there are enough databases that don't allow that that it can't be the default. Use separate queries by default, which works everywhere.

     # File lib/sequel/dataset/sql.rb
1254 def multi_insert_sql_strategy
1255   :separate
1256 end
native_function_name(emulated_function) click to toggle source

Get the native function name given the emulated function name.

     # File lib/sequel/dataset/sql.rb
1260 def native_function_name(emulated_function)
1261   emulated_function
1262 end
qualified_column_name(column, table) click to toggle source

Returns a qualified column name (including a table name) if the column name isn't already qualified.

     # File lib/sequel/dataset/sql.rb
1266 def qualified_column_name(column, table)
1267   if column.is_a?(Symbol)
1268     c_table, column, _ = split_symbol(column)
1269     unless c_table
1270       case table
1271       when Symbol
1272         schema, table, t_alias = split_symbol(table)
1273         t_alias ||= Sequel::SQL::QualifiedIdentifier.new(schema, table) if schema
1274       when Sequel::SQL::AliasedExpression
1275         t_alias = table.alias
1276       end
1277       c_table = t_alias || table
1278     end
1279     ::Sequel::SQL::QualifiedIdentifier.new(c_table, column)
1280   else
1281     column
1282   end
1283 end
qualified_expression(e, table) click to toggle source

Qualify the given expression to the given table.

     # File lib/sequel/dataset/sql.rb
1286 def qualified_expression(e, table)
1287   Qualifier.new(table).transform(e)
1288 end
select_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1290 def select_columns_sql(sql)
1291   sql << ' '
1292   column_list_append(sql, @opts[:select])
1293 end
select_compounds_sql(sql) click to toggle source

Modify the sql to add a dataset to the via an EXCEPT, INTERSECT, or UNION clause. This uses a subselect for the compound datasets used, because using parantheses doesn't work on all databases.

     # File lib/sequel/dataset/sql.rb
1309 def select_compounds_sql(sql)
1310   return unless c = @opts[:compounds]
1311   c.each do |type, dataset, all|
1312     sql << ' ' << type.to_s.upcase
1313     sql << ' ALL' if all
1314     sql << ' '
1315     compound_dataset_sql_append(sql, dataset)
1316   end
1317 end
select_distinct_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1295 def select_distinct_sql(sql)
1296   if distinct = @opts[:distinct]
1297     sql << " DISTINCT"
1298     unless distinct.empty?
1299       sql << " ON ("
1300       expression_list_append(sql, distinct)
1301       sql << ')'
1302     end
1303   end
1304 end
select_from_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1319 def select_from_sql(sql)
1320   if f = @opts[:from]
1321     sql << ' FROM '
1322     source_list_append(sql, f)
1323   elsif f = empty_from_sql
1324     sql << f
1325   end
1326 end
select_group_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1328 def select_group_sql(sql)
1329   if group = @opts[:group]
1330     sql << " GROUP BY "
1331     if go = @opts[:group_options]
1332       if go == :"grouping sets"
1333         sql << go.to_s.upcase << '('
1334         grouping_element_list_append(sql, group)
1335         sql << ')'
1336       elsif uses_with_rollup?
1337         expression_list_append(sql, group)
1338         sql << " WITH " << go.to_s.upcase
1339       else
1340         sql << go.to_s.upcase << '('
1341         expression_list_append(sql, group)
1342         sql << ')'
1343       end
1344     else
1345       expression_list_append(sql, group)
1346     end
1347   end
1348 end
select_having_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1350 def select_having_sql(sql)
1351   if having = @opts[:having]
1352     sql << " HAVING "
1353     literal_append(sql, having)
1354   end
1355 end
select_join_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1357 def select_join_sql(sql)
1358   if js = @opts[:join]
1359     js.each{|j| literal_append(sql, j)}
1360   end
1361 end
select_limit_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1363 def select_limit_sql(sql)
1364   if l = @opts[:limit]
1365     sql << " LIMIT "
1366     literal_append(sql, l)
1367     if o = @opts[:offset]
1368       sql << " OFFSET "
1369       literal_append(sql, o)
1370     end
1371   elsif @opts[:offset]
1372     select_only_offset_sql(sql)
1373   end
1374 end
select_lock_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1376 def select_lock_sql(sql)
1377   case l = @opts[:lock]
1378   when :update
1379     sql << ' FOR UPDATE'
1380   when String
1381     sql << ' ' << l
1382   end
1383 end
select_only_offset_sql(sql) click to toggle source

Used only if there is an offset and no limit, making it easier to override in the adapter, as many databases do not support just a plain offset with no limit.

     # File lib/sequel/dataset/sql.rb
1388 def select_only_offset_sql(sql)
1389   sql << " OFFSET "
1390   literal_append(sql, @opts[:offset])
1391 end
select_order_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1393 def select_order_sql(sql)
1394   if o = @opts[:order]
1395     sql << " ORDER BY "
1396     expression_list_append(sql, o)
1397   end
1398 end
select_select_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1402 def select_select_sql(sql)
1403   sql << 'SELECT'
1404 end
select_where_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1406 def select_where_sql(sql)
1407   if w = @opts[:where]
1408     sql << " WHERE "
1409     literal_append(sql, w)
1410   end
1411 end
select_with_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1415 def select_with_sql(sql)
1416   return unless supports_cte?
1417   ws = opts[:with]
1418   return if !ws || ws.empty?
1419   sql << select_with_sql_base
1420   c = false
1421   comma = ', '
1422   ws.each do |w|
1423     sql << comma if c
1424     quote_identifier_append(sql, w[:name])
1425     if args = w[:args]
1426      sql << '('
1427      identifier_list_append(sql, args)
1428      sql << ')'
1429     end
1430     sql << ' AS '
1431     literal_dataset_append(sql, w[:dataset])
1432     c ||= true
1433   end
1434   sql << ' '
1435 end
select_with_sql_base() click to toggle source
     # File lib/sequel/dataset/sql.rb
1440 def select_with_sql_base
1441   "WITH "
1442 end
skip_symbol_cache?() click to toggle source

Whether the symbol cache should be skipped when literalizing the dataset

     # File lib/sequel/dataset/sql.rb
1445 def skip_symbol_cache?
1446   @opts[:skip_symbol_cache]
1447 end
source_list_append(sql, sources) click to toggle source

Append literalization of array of sources/tables to SQL string, raising an Error if there are no sources.

     # File lib/sequel/dataset/sql.rb
1451 def source_list_append(sql, sources)
1452   raise(Error, 'No source specified for query') if sources.nil? || sources == []
1453   identifier_list_append(sql, sources)
1454 end
split_symbol(sym) click to toggle source

Delegate to Sequel.split_symbol.

     # File lib/sequel/dataset/sql.rb
1457 def split_symbol(sym)
1458   Sequel.split_symbol(sym)
1459 end
sql_string_origin() click to toggle source

The string that is appended to to create the SQL query, the empty string by default.

     # File lib/sequel/dataset/sql.rb
1463 def sql_string_origin
1464   String.new
1465 end
sqltime_precision() click to toggle source

The precision to use for SQLTime instances (time column values without dates). Defaults to timestamp_precision.

     # File lib/sequel/dataset/sql.rb
1469 def sqltime_precision
1470   timestamp_precision
1471 end
static_sql(sql) click to toggle source

SQL to use if this dataset uses static SQL. Since static SQL can be a PlaceholderLiteralString in addition to a String, we literalize nonstrings. If there is an append_sql for this dataset, append to that SQL instead of returning the value.

     # File lib/sequel/dataset/sql.rb
1477 def static_sql(sql)
1478   if append_sql = @opts[:append_sql]
1479     if sql.is_a?(String)
1480       append_sql << sql
1481     else
1482       literal_append(append_sql, sql)
1483     end
1484   else
1485     if sql.is_a?(String)
1486       sql
1487     else
1488       literal(sql)
1489     end
1490   end
1491 end
subselect_sql_append(sql, ds) click to toggle source

Append literalization of the subselect to SQL string.

     # File lib/sequel/dataset/sql.rb
1494 def subselect_sql_append(sql, ds)
1495   ds.clone(:append_sql=>sql).sql
1496 end
timestamp_precision() click to toggle source

The number of decimal digits of precision to use in timestamps.

     # File lib/sequel/dataset/sql.rb
1499 def timestamp_precision
1500   supports_timestamp_usecs? ? 6 : 0
1501 end
update_order_sql(sql)
Alias for: select_order_sql
update_returning_sql(sql)
update_set_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1509 def update_set_sql(sql)
1510   sql << ' SET '
1511   values = @opts[:values]
1512   if values.is_a?(Hash)
1513     update_sql_values_hash(sql, values)
1514   else
1515     sql << values
1516   end
1517 end
update_sql_values_hash(sql, values) click to toggle source
     # File lib/sequel/dataset/sql.rb
1519 def update_sql_values_hash(sql, values)
1520   c = false
1521   eq = ' = '
1522   values.each do |k, v|
1523     sql << ', ' if c
1524     if k.is_a?(String) && !k.is_a?(LiteralString)
1525       quote_identifier_append(sql, k)
1526     else
1527       literal_append(sql, k)
1528     end
1529     sql << eq
1530     literal_append(sql, v)
1531     c ||= true
1532   end
1533 end
update_table_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1503 def update_table_sql(sql)
1504   sql << ' '
1505   source_list_append(sql, @opts[:from])
1506   select_join_sql(sql) if supports_modifying_joins?
1507 end
update_update_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1535 def update_update_sql(sql)
1536   sql << 'UPDATE'
1537 end
update_where_sql(sql)
Alias for: select_where_sql
update_with_sql(sql)
Alias for: select_with_sql