class Sequel::Dataset

  1. lib/sequel/dataset.rb
  2. lib/sequel/dataset/actions.rb
  3. lib/sequel/dataset/dataset_module.rb
  4. lib/sequel/dataset/features.rb
  5. lib/sequel/dataset/graph.rb
  6. lib/sequel/dataset/misc.rb
  7. lib/sequel/dataset/placeholder_literalizer.rb
  8. lib/sequel/dataset/prepared_statements.rb
  9. lib/sequel/dataset/query.rb
  10. lib/sequel/dataset/sql.rb
  11. lib/sequel/model/associations.rb
  12. lib/sequel/model/base.rb
  13. lib/sequel/sql.rb
  14. show all
Superclass: Object

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 many of the Enumerable methods, such as map and inject. Note that there are some methods that Dataset defines that override methods defined in Enumerable and result in different behavior, such as select and group_by.

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

Methods

Public Class

  1. clause_methods
  2. def_sql_method
  3. new
  4. register_extension

Public Instance

  1. <<
  2. ==
  3. []
  4. add_graph_aliases
  5. aliased_expression_sql_append
  6. all
  7. array_sql_append
  8. as_hash
  9. avg
  10. bind
  11. boolean_constant_sql_append
  12. call
  13. case_expression_sql_append
  14. cast_sql_append
  15. clone
  16. column_all_sql_append
  17. columns
  18. columns!
  19. complex_expression_sql_append
  20. constant_sql_append
  21. count
  22. current_datetime
  23. db
  24. delayed_evaluation_sql_append
  25. delete
  26. distinct
  27. dup
  28. each
  29. each_server
  30. empty?
  31. eql?
  32. escape_like
  33. except
  34. exclude
  35. exclude_having
  36. exists
  37. extension
  38. filter
  39. first
  40. first!
  41. first_source
  42. first_source_alias
  43. first_source_table
  44. for_update
  45. freeze
  46. from
  47. from_self
  48. function_sql_append
  49. get
  50. graph
  51. grep
  52. group
  53. group_and_count
  54. group_append
  55. group_by
  56. group_cube
  57. group_rollup
  58. grouping_sets
  59. hash
  60. having
  61. import
  62. insert
  63. insert_sql
  64. inspect
  65. intersect
  66. invert
  67. join
  68. join_clause_sql_append
  69. join_on_clause_sql_append
  70. join_table
  71. join_using_clause_sql_append
  72. joined_dataset?
  73. last
  74. lateral
  75. limit
  76. literal_append
  77. lock_style
  78. map
  79. max
  80. merge
  81. merge_delete
  82. merge_insert
  83. merge_sql
  84. merge_update
  85. merge_using
  86. min
  87. multi_insert
  88. multi_insert_sql
  89. naked
  90. negative_boolean_constant_sql_append
  91. nowait
  92. offset
  93. opts
  94. or
  95. order
  96. order_append
  97. order_by
  98. order_more
  99. order_prepend
  100. ordered_expression_sql_append
  101. paged_each
  102. placeholder_literal_string_sql_append
  103. prepare
  104. provides_accurate_rows_matched?
  105. qualified_identifier_sql_append
  106. qualify
  107. quote_identifier_append
  108. quote_identifiers?
  109. quote_schema_table_append
  110. quoted_identifier_append
  111. recursive_cte_requires_column_aliases?
  112. requires_placeholder_type_specifiers?
  113. requires_sql_standard_datetimes?
  114. returning
  115. reverse
  116. reverse_order
  117. row_number_column
  118. row_proc
  119. schema_and_table
  120. select
  121. select_all
  122. select_append
  123. select_group
  124. select_hash
  125. select_hash_groups
  126. select_map
  127. select_more
  128. select_order_map
  129. server
  130. server?
  131. set_graph_aliases
  132. single_record
  133. single_record!
  134. single_value
  135. single_value!
  136. skip_limit_check
  137. skip_locked
  138. split_alias
  139. split_qualifiers
  140. sql
  141. subscript_sql_append
  142. sum
  143. supports_cte?
  144. supports_cte_in_subqueries?
  145. supports_deleting_joins?
  146. supports_derived_column_lists?
  147. supports_distinct_on?
  148. supports_group_cube?
  149. supports_group_rollup?
  150. supports_grouping_sets?
  151. supports_insert_select?
  152. supports_intersect_except?
  153. supports_intersect_except_all?
  154. supports_is_true?
  155. supports_join_using?
  156. supports_lateral_subqueries?
  157. supports_limits_in_correlated_subqueries?
  158. supports_merge?
  159. supports_modifying_joins?
  160. supports_multiple_column_in?
  161. supports_nowait?
  162. supports_offsets_in_correlated_subqueries?
  163. supports_ordered_distinct_on?
  164. supports_placeholder_literalizer?
  165. supports_regexp?
  166. supports_replace?
  167. supports_returning?
  168. supports_select_all_and_column?
  169. supports_skip_locked?
  170. supports_timestamp_timezones?
  171. supports_timestamp_usecs?
  172. supports_updating_joins?
  173. supports_where_true?
  174. supports_window_clause?
  175. supports_window_function_frame_option?
  176. supports_window_functions?
  177. to_hash
  178. to_hash_groups
  179. truncate
  180. truncate_sql
  181. unfiltered
  182. ungraphed
  183. ungrouped
  184. union
  185. unlimited
  186. unordered
  187. unqualified_column_for
  188. unused_table_alias
  189. update
  190. update_sql
  191. where
  192. where_all
  193. where_each
  194. where_single_value
  195. window
  196. window_sql_append
  197. with
  198. with_extend
  199. with_quote_identifiers
  200. with_recursive
  201. with_row_proc
  202. with_sql
  203. with_sql_all
  204. with_sql_delete
  205. with_sql_each
  206. with_sql_first
  207. with_sql_insert
  208. with_sql_single_value

Protected Instance

  1. _columns
  2. _import
  3. _select_map_multiple
  4. _select_map_single
  5. cache
  6. cache_get
  7. cache_set
  8. clear_columns_cache
  9. compound_clone
  10. compound_from_self
  11. options_overlap
  12. simple_select_all?
  13. single_value_ds
  14. to_prepared_statement

Constants

OPTS = Sequel::OPTS  
TRUE_FREEZE = RUBY_VERSION >= '2.4'  

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

Constants

COLUMN_CHANGE_OPTS = [:select, :sql, :from, :join].freeze  

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

CONDITIONED_JOIN_TYPES = [:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left].freeze  

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 = [].freeze  
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 = ((CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table]).freeze  

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

NON_SQL_OPTIONS = [:server, :graph, :row_proc, :quote_identifiers, :skip_symbol_cache].freeze  

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 = ((<<-METHS).split.map(&:to_sym) + JOIN_METHODS).freeze  

Methods that return modified datasets

SIMPLE_SELECT_ALL_ALLOWED_FROM = [Symbol, SQL::Identifier, SQL::QualifiedIdentifier].freeze  

From types allowed to be considered a simple_select_all

UNCONDITIONED_JOIN_TYPES = [:natural, :natural_left, :natural_right, :natural_full, :cross].freeze  

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 Instance Aliases

_clone -> clone

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

Public Class methods

register_extension(ext, mod=nil, &block)

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.

[show source]
   # 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 = nil || (return self))

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.

[show source]
   # File lib/sequel/dataset/query.rb
84 def clone(opts = nil || (return self))
85   # return self used above because clone is called by almost all
86   # other query methods, and it is the fastest approach
87   c = super(:freeze=>false)
88   c.opts.merge!(opts)
89   unless opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
90     c.clear_columns_cache
91   end
92   c.freeze
93 end
distinct(*args, &block)

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 emulating 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+.

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

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
[show source]
    # File lib/sequel/dataset/query.rb
150 def except(dataset, opts=OPTS)
151   raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
152   raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
153   compound_clone(:except, dataset, opts)
154 end
exclude(*cond, &block)

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'))
[show source]
    # File lib/sequel/dataset/query.rb
180 def exclude(*cond, &block)
181   add_filter(:where, cond, true, &block)
182 end
exclude_having(*cond, &block)

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.

[show source]
    # File lib/sequel/dataset/query.rb
191 def exclude_having(*cond, &block)
192   add_filter(:having, cond, true, &block)
193 end
extension(*a)

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.

[show source]
    # File lib/sequel/dataset/query.rb
199 def extension(*a)
200   c = _clone(:freeze=>false)
201   c.send(:_extension!, a)
202   c.freeze
203 end
filter(*cond, &block)

Alias for where.

[show source]
    # File lib/sequel/dataset/query.rb
215 def filter(*cond, &block)
216   where(*cond, &block)
217 end
for_update()

Returns a cloned dataset with a :update lock style.

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

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

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)
[show source]
    # File lib/sequel/dataset/query.rb
283 def from_self(opts=OPTS)
284   fs = {}
285   @opts.keys.each{|k| fs[k] = nil unless non_sql_option?(k)}
286   pr = proc do
287     c = clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self)
288     if cols = _columns
289       c.send(:columns=, cols)
290     end
291     c
292   end
293 
294   opts.empty? ? cached_dataset(:_from_self_ds, &pr) : pr.call
295 end
grep(columns, patterns, opts=OPTS)

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 '\'))
[show source]
    # File lib/sequel/dataset/query.rb
332 def grep(columns, patterns, opts=OPTS)
333   column_op = opts[:all_columns] ? :AND : :OR
334   if opts[:all_patterns]
335     conds = Array(patterns).map do |pat|
336       SQL::BooleanExpression.new(column_op, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
337     end
338     where(SQL::BooleanExpression.new(:AND, *conds))
339   else
340     conds = Array(columns).map do |c|
341       SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
342     end
343     where(SQL::BooleanExpression.new(column_op, *conds))
344   end
345 end
group(*columns, &block)

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)
[show source]
    # File lib/sequel/dataset/query.rb
354 def group(*columns, &block)
355   virtual_row_columns(columns, block)
356   clone(:group => (columns.compact.empty? ? nil : columns.freeze))
357 end
group_and_count(*columns, &block)

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}, ...]
[show source]
    # File lib/sequel/dataset/query.rb
385 def group_and_count(*columns, &block)
386   select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT)
387 end
group_append(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
395 def group_append(*columns, &block)
396   columns = @opts[:group] + columns if @opts[:group]
397   group(*columns, &block)
398 end
group_by(*columns, &block)

Alias of group

[show source]
    # File lib/sequel/dataset/query.rb
360 def group_by(*columns, &block)
361   group(*columns, &block)
362 end
group_cube()

Adds the appropriate CUBE syntax to GROUP BY.

[show source]
    # File lib/sequel/dataset/query.rb
401 def group_cube
402   raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
403   clone(:group_options=>:cube)
404 end
group_rollup()

Adds the appropriate ROLLUP syntax to GROUP BY.

[show source]
    # File lib/sequel/dataset/query.rb
407 def group_rollup
408   raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
409   clone(:group_options=>:rollup)
410 end
grouping_sets()

Adds the appropriate GROUPING SETS syntax to GROUP BY.

[show source]
    # File lib/sequel/dataset/query.rb
413 def grouping_sets
414   raise Error, "GROUP BY GROUPING SETS not supported on #{db.database_type}" unless supports_grouping_sets?
415   clone(:group_options=>:"grouping sets")
416 end
having(*cond, &block)

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)
[show source]
    # File lib/sequel/dataset/query.rb
422 def having(*cond, &block)
423   add_filter(:having, cond, &block)
424 end
intersect(dataset, opts=OPTS)

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
[show source]
    # File lib/sequel/dataset/query.rb
443 def intersect(dataset, opts=OPTS)
444   raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
445   raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
446   compound_clone(:intersect, dataset, opts)
447 end
invert()

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.

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

Alias of inner_join

[show source]
    # File lib/sequel/dataset/query.rb
475 def join(*args, &block)
476   inner_join(*args, &block)
477 end
join_table(type, table, expr=nil, options=OPTS, &block)

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.

:join_using

Force the using of JOIN USING, even if expr is not an array of symbols.

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

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))
[show source]
    # File lib/sequel/dataset/query.rb
633 def lateral
634   cached_dataset(:_lateral_ds){clone(:lateral=>true)}
635 end
limit(l, o = (no_offset = true; nil))

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
[show source]
    # File lib/sequel/dataset/query.rb
647 def limit(l, o = (no_offset = true; nil))
648   return from_self.limit(l, o) if @opts[:sql]
649 
650   if l.is_a?(Range)
651     no_offset = false
652     o = l.first
653     l = l.last - l.first + (l.exclude_end? ? 0 : 1)
654   end
655   l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
656   if l.is_a?(Integer)
657     raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
658   end
659 
660   ds = clone(:limit=>l)
661   ds = ds.offset(o) unless no_offset
662   ds
663 end
lock_style(style)

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
[show source]
    # File lib/sequel/dataset/query.rb
677 def lock_style(style)
678   clone(:lock => style)
679 end
merge_delete(&block)

Return a dataset with a WHEN MATCHED THEN DELETE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_delete
# WHEN MATCHED THEN DELETE

merge_delete{a > 30}
# WHEN MATCHED AND (a > 30) THEN DELETE
[show source]
    # File lib/sequel/dataset/query.rb
690 def merge_delete(&block)
691   _merge_when(:type=>:delete, &block)
692 end
merge_insert(*values, &block)

Return a dataset with a WHEN NOT MATCHED THEN INSERT clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

The arguments provided can be any arguments that would be accepted by insert.

merge_insert(i1: :i2, a: Sequel[:b]+11)
# WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))

merge_insert(:i2, Sequel[:b]+11){a > 30}
# WHEN NOT MATCHED AND (a > 30) THEN INSERT VALUES (i2, (b + 11))
[show source]
    # File lib/sequel/dataset/query.rb
706 def merge_insert(*values, &block)
707   _merge_when(:type=>:insert, :values=>values, &block)
708 end
merge_update(values, &block)

Return a dataset with a WHEN MATCHED THEN UPDATE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20)
# WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

merge_update(i1: :i2){a > 30}
# WHEN MATCHED AND (a > 30) THEN UPDATE SET i1 = i2
[show source]
    # File lib/sequel/dataset/query.rb
719 def merge_update(values, &block)
720   _merge_when(:type=>:update, :values=>values, &block)
721 end
merge_using(source, join_condition)

Return a dataset with the source and join condition to use for the MERGE statement.

merge_using(:m2, i1: :i2)
# USING m2 ON (i1 = i2)
[show source]
    # File lib/sequel/dataset/query.rb
727 def merge_using(source, join_condition)
728   clone(:merge_using => [source, join_condition].freeze)
729 end
naked()

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}]
[show source]
    # File lib/sequel/dataset/query.rb
736 def naked
737   cached_dataset(:_naked_ds){with_row_proc(nil)}
738 end
nowait()

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
[show source]
    # File lib/sequel/dataset/query.rb
745 def nowait
746   cached_dataset(:_nowait_ds) do
747     raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait?
748     clone(:nowait=>true)
749   end
750 end
offset(o)

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 the offset if you’ve called offset first.

DB[:items].offset(10) # SELECT * FROM items OFFSET 10
[show source]
    # File lib/sequel/dataset/query.rb
757 def offset(o)
758   o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
759   if o.is_a?(Integer)
760     raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
761   end
762   clone(:offset => o)
763 end
or(*cond, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
771 def or(*cond, &block)
772   if @opts[:where].nil?
773     self
774   else
775     add_filter(:where, cond, false, :OR, &block)
776   end
777 end
order(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
793 def order(*columns, &block)
794   virtual_row_columns(columns, block)
795   clone(:order => (columns.compact.empty?) ? nil : columns.freeze)
796 end
order_append(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
803 def order_append(*columns, &block)
804   columns = @opts[:order] + columns if @opts[:order]
805   order(*columns, &block)
806 end
order_by(*columns, &block)

Alias of order

[show source]
    # File lib/sequel/dataset/query.rb
809 def order_by(*columns, &block)
810   order(*columns, &block)
811 end
order_more(*columns, &block)

Alias of order_append.

[show source]
    # File lib/sequel/dataset/query.rb
814 def order_more(*columns, &block)
815   order_append(*columns, &block)
816 end
order_prepend(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
823 def order_prepend(*columns, &block)
824   ds = order(*columns, &block)
825   @opts[:order] ? ds.order_append(*@opts[:order]) : ds
826 end
qualify(table=(cache=true; first_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)
[show source]
    # File lib/sequel/dataset/query.rb
835 def qualify(table=(cache=true; first_source))
836   o = @opts
837   return self if o[:sql]
838 
839   pr = proc do
840     h = {}
841     (o.keys & QUALIFY_KEYS).each do |k|
842       h[k] = qualified_expression(o[k], table)
843     end
844     h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty?
845     clone(h)
846   end
847 
848   cache ? cached_dataset(:_qualify_ds, &pr) : pr.call
849 end
returning(*values)

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
[show source]
    # File lib/sequel/dataset/query.rb
869 def returning(*values)
870   if values.empty?
871     cached_dataset(:_returning_ds) do
872       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
873       clone(:returning=>EMPTY_ARRAY)
874     end
875   else
876     raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
877     clone(:returning=>values.freeze)
878   end
879 end
reverse(*order, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
888 def reverse(*order, &block)
889   if order.empty? && !block
890     cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))}
891   else
892     virtual_row_columns(order, block)
893     order(*invert_order(order.empty? ? @opts[:order] : order.freeze))
894   end
895 end
reverse_order(*order, &block)

Alias of reverse

[show source]
    # File lib/sequel/dataset/query.rb
898 def reverse_order(*order, &block)
899   reverse(*order, &block)
900 end
select(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
909 def select(*columns, &block)
910   virtual_row_columns(columns, block)
911   clone(:select => columns.freeze)
912 end
select_all(*tables)

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
[show source]
    # File lib/sequel/dataset/query.rb
921 def select_all(*tables)
922   if tables.empty?
923     cached_dataset(:_select_all_ds){clone(:select => nil)}
924   else
925     select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze)
926   end
927 end
select_append(*columns, &block)

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
[show source]
    # File lib/sequel/dataset/query.rb
936 def select_append(*columns, &block)
937   cur_sel = @opts[:select]
938   if !cur_sel || cur_sel.empty?
939     unless supports_select_all_and_column?
940       return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_append(*columns, &block)
941     end
942     cur_sel = [WILDCARD]
943   end
944   select(*(cur_sel + columns), &block)
945 end
select_group(*columns, &block)

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)
[show source]
    # File lib/sequel/dataset/query.rb
956 def select_group(*columns, &block)
957   virtual_row_columns(columns, block)
958   select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
959 end
select_more(*columns, &block)

Alias for select_append.

[show source]
    # File lib/sequel/dataset/query.rb
962 def select_more(*columns, &block)
963   select_append(*columns, &block)
964 end
server(servr)

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
[show source]
    # File lib/sequel/dataset/query.rb
975 def server(servr)
976   clone(:server=>servr)
977 end
server?(server)

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.

[show source]
    # File lib/sequel/dataset/query.rb
982 def server?(server)
983   if db.sharded? && !opts[:server]
984     server(server)
985   else
986     self
987   end
988 end
skip_limit_check()

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

[show source]
    # File lib/sequel/dataset/query.rb
991 def skip_limit_check
992   cached_dataset(:_skip_limit_check_ds) do
993     clone(:skip_limit_check=>true)
994   end
995 end
skip_locked()

Skip locked rows when returning results from this dataset.

[show source]
     # File lib/sequel/dataset/query.rb
 998 def skip_locked
 999   cached_dataset(:_skip_locked_ds) do
1000     raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked?
1001     clone(:skip_locked=>true)
1002   end
1003 end
unfiltered()

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
[show source]
     # File lib/sequel/dataset/query.rb
1009 def unfiltered
1010   cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)}
1011 end
ungrouped()

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
[show source]
     # File lib/sequel/dataset/query.rb
1017 def ungrouped
1018   cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)}
1019 end
union(dataset, opts=OPTS)

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
[show source]
     # File lib/sequel/dataset/query.rb
1037 def union(dataset, opts=OPTS)
1038   compound_clone(:union, dataset, opts)
1039 end
unlimited()

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

DB[:items].limit(10, 20).unlimited # SELECT * FROM items
[show source]
     # File lib/sequel/dataset/query.rb
1044 def unlimited
1045   cached_dataset(:_unlimited_ds){clone(:limit=>nil, :offset=>nil)}
1046 end
unordered()

Returns a copy of the dataset with no order.

DB[:items].order(:a).unordered # SELECT * FROM items
[show source]
     # File lib/sequel/dataset/query.rb
1051 def unordered
1052   cached_dataset(:_unordered_ds){clone(:order=>nil)}
1053 end
where(*cond, &block)

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.

[show source]
     # File lib/sequel/dataset/query.rb
1097 def where(*cond, &block)
1098   add_filter(:where, cond, &block)
1099 end
window(name, opts)

Return a clone of the dataset with an addition named window that can be referenced in window functions. See Sequel::SQL::Window for a list of options that can be passed in. Example:

DB[:items].window(:w, partition: :c1, order: :c2)
# SELECT * FROM items WINDOW w AS (PARTITION BY c1 ORDER BY c2)
[show source]
     # File lib/sequel/dataset/query.rb
1107 def window(name, opts)
1108   clone(:window=>((@opts[:window]||EMPTY_ARRAY) + [[name, SQL::Window.new(opts)].freeze]).freeze)
1109 end
with(name, dataset, opts=OPTS)

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

:materialized

Set to false to force inlining of the CTE, or true to force not inlining the CTE (PostgreSQL 12+/SQLite 3.35+).

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
[show source]
     # File lib/sequel/dataset/query.rb
1122 def with(name, dataset, opts=OPTS)
1123   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1124   if hoist_cte?(dataset)
1125     s, ds = hoist_cte(dataset)
1126     s.with(name, ds, opts)
1127   else
1128     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze)
1129   end
1130 end
with_extend(*mods, &block)

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.

[show source]
     # File lib/sequel/dataset/query.rb
1207 def with_extend(*mods, &block)
1208   c = _clone(:freeze=>false)
1209   c.extend(*mods) unless mods.empty?
1210   c.extend(DatasetModule.new(&block)) if block
1211   c.freeze
1212 end
with_recursive(name, nonrecursive, recursive, opts=OPTS)

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.

PostgreSQL 14+ Options:

:cycle

Stop recursive searching when a cycle is detected. Includes two columns in the result of the CTE, a cycle column indicating whether a cycle was detected for the current row, and a path column for the path traversed to get to the current row. If given, must be a hash with the following keys:

:columns

(required) The column or array of columns to use to detect a cycle. If the value of these columns match columns already traversed, then a cycle is detected, and recursive searching will not traverse beyond the cycle (the CTE will include the row where the cycle was detected).

:cycle_column

The name of the cycle column in the output, defaults to :is_cycle.

:cycle_value

The value of the cycle column in the output if the current row was detected as a cycle, defaults to true.

:noncycle_value

The value of the cycle column in the output if the current row was not detected as a cycle, defaults to false. Only respected if :cycle_value is given.

:path_column

The name of the path column in the output, defaults to :path.

:search

Include an order column in the result of the CTE that allows for breadth or depth first searching. If given, must be a hash with the following keys:

:by

(required) The column or array of columns to search by.

:order_column

The name of the order column in the output, defaults to :ordercol.

:type

Set to :breadth to use breadth-first searching (depth-first searching is the default).

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

DB[:t].with_recursive(:t,
  DB[:i1].where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select_all(:i1),
  search: {by: :id, type: :breadth},
  cycle: {columns: :id, cycle_value: 1, noncycle_value: 2})

# WITH RECURSIVE t AS (
#     SELECT * FROM i1 WHERE (parent_id IS NULL)
#     UNION ALL
#     (SELECT i1.* FROM i1 INNER JOIN t ON (t.id = i1.parent_id))
#   )
#   SEARCH BREADTH FIRST BY id SET ordercol
#   CYCLE id SET is_cycle TO 1 DEFAULT 2 USING path
# SELECT * FROM t
[show source]
     # File lib/sequel/dataset/query.rb
1188 def with_recursive(name, nonrecursive, recursive, opts=OPTS)
1189   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1190   if hoist_cte?(nonrecursive)
1191     s, ds = hoist_cte(nonrecursive)
1192     s.with_recursive(name, ds, recursive, opts)
1193   elsif hoist_cte?(recursive)
1194     s, ds = hoist_cte(recursive)
1195     s.with_recursive(name, nonrecursive, ds, opts)
1196   else
1197     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)
1198   end
1199 end
with_row_proc(callable)

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}]
[show source]
     # File lib/sequel/dataset/query.rb
1229 def with_row_proc(callable)
1230   clone(:row_proc=>callable)
1231 end
with_sql(sql, *args)

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)

[show source]
     # File lib/sequel/dataset/query.rb
1263 def with_sql(sql, *args)
1264   if sql.is_a?(Symbol)
1265     sql = public_send(sql, *args)
1266   else
1267     sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
1268   end
1269   clone(:sql=>sql)
1270 end

Protected Instance methods

compound_clone(type, dataset, opts)

Add the dataset to the list of compounds

[show source]
     # File lib/sequel/dataset/query.rb
1275 def compound_clone(type, dataset, opts)
1276   if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds?
1277     s, ds = hoist_cte(dataset)
1278     return s.compound_clone(type, ds, opts)
1279   end
1280   ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze)
1281   opts[:from_self] == false ? ds : ds.from_self(opts)
1282 end
options_overlap(opts)

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

[show source]
     # File lib/sequel/dataset/query.rb
1285 def options_overlap(opts)
1286   !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty?
1287 end
simple_select_all?()

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

SELECT * FROM table
SELECT table.* FROM table
[show source]
     # File lib/sequel/dataset/query.rb
1296 def simple_select_all?
1297   return false unless (f = @opts[:from]) && f.length == 1
1298   o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)}
1299   from = f.first
1300   from = from.expression if from.is_a?(SQL::AliasedExpression)
1301 
1302   if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)}
1303     case o.length
1304     when 1
1305       true
1306     when 2
1307       (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1308     else
1309       false
1310     end
1311   else
1312     false
1313   end
1314 end

2 - Methods that execute code on the database

Constants

ACTION_METHODS = (<<-METHS).split.map(&:to_sym).freeze  

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

COLUMNS_CLONE_OPTIONS = {:distinct => nil, :limit => 0, :offset=>nil, :where=>nil, :having=>nil, :order=>nil, :row_proc=>nil, :graph=>nil, :eager_graph=>nil}.freeze  

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

COUNT_SELECT = Sequel.function(:count).*.as(:count)  
EMPTY_SELECT = Sequel::SQL::AliasedExpression.new(1, :one)  

Public Instance Aliases

with_sql_update -> with_sql_delete

Public Instance methods

<<(arg)

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)
[show source]
   # File lib/sequel/dataset/actions.rb
28 def <<(arg)
29   insert(arg)
30   self
31 end
[](*conditions)

Returns the first record matching the conditions. Examples:

DB[:table][id: 1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=>1}
[show source]
   # 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)

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}
[show source]
   # 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)

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.

[show source]
    # File lib/sequel/dataset/actions.rb
831 def as_hash(key_column, value_column = nil, opts = OPTS)
832   h = opts[:hash] || {}
833   meth = opts[:all] ? :all : :each
834   if value_column
835     return naked.as_hash(key_column, value_column, opts) if row_proc
836     if value_column.is_a?(Array)
837       if key_column.is_a?(Array)
838         public_send(meth){|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
839       else
840         public_send(meth){|r| h[r[key_column]] = r.values_at(*value_column)}
841       end
842     else
843       if key_column.is_a?(Array)
844         public_send(meth){|r| h[r.values_at(*key_column)] = r[value_column]}
845       else
846         public_send(meth){|r| h[r[key_column]] = r[value_column]}
847       end
848     end
849   elsif key_column.is_a?(Array)
850     public_send(meth){|r| h[key_column.map{|k| r[k]}] = r}
851   else
852     public_send(meth){|r| h[r[key_column]] = r}
853   end
854   h
855 end
avg(arg=(no_arg = true), &block)

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
[show source]
   # File lib/sequel/dataset/actions.rb
61 def avg(arg=(no_arg = true), &block)
62   arg = Sequel.virtual_row(&block) if no_arg
63   _aggregate(:avg, arg)
64 end
columns()

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]
[show source]
   # File lib/sequel/dataset/actions.rb
75 def columns
76   _columns || columns!
77 end
columns!()

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

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

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
[show source]
    # File lib/sequel/dataset/actions.rb
108 def count(arg=(no_arg=true), &block)
109   if no_arg && !block
110     cached_dataset(:_count_ds) do
111       aggregate_dataset.select(COUNT_SELECT).single_value_ds
112     end.single_value!.to_i
113   else
114     if block
115       if no_arg
116         arg = Sequel.virtual_row(&block)
117       else
118         raise Error, 'cannot provide both argument and block to Dataset#count'
119       end
120     end
121 
122     _aggregate(:count, arg)
123   end
124 end
delete(&block)

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

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

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.

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

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

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

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

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

[show source]
    # File lib/sequel/dataset/actions.rb
251 def first!(*args, &block)
252   first(*args, &block) || raise(Sequel::NoMatchingRow.new(self))
253 end
get(column=(no_arg=true; nil), &block)

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

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 if necessary.

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)

or, if the database supports it:

# INSERT INTO table (x, y) VALUES (1, 2), (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. When a transaction is not required, this option controls the maximum number of values to insert with a single statement; it does not force the use of a transaction.

:return

When this is set to :primary_key, returns an array of autoincremented primary key values for the rows inserted. This does not have an effect if values is a Dataset.

:server

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

:slice

Same as :commit_every, :commit_every takes precedence.

[show source]
    # File lib/sequel/dataset/actions.rb
348 def import(columns, values, opts=OPTS)
349   return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
350 
351   return if values.empty?
352   raise(Error, 'Using Sequel::Dataset#import with an empty column array is not allowed') if columns.empty?
353   ds = opts[:server] ? server(opts[:server]) : self
354   
355   if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
356     offset = 0
357     rows = []
358     while offset < values.length
359       rows << ds._import(columns, values[offset, slice_size], opts)
360       offset += slice_size
361     end
362     rows.flatten
363   else
364     ds._import(columns, values, opts)
365   end
366 end
insert(*values, &block)

Inserts values into the associated table. The returned value is generally the value of the autoincremented primary key for the inserted row, assuming that 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
[show source]
    # File lib/sequel/dataset/actions.rb
404 def insert(*values, &block)
405   sql = insert_sql(*values)
406   if uses_returning?(:insert)
407     returning_fetch_rows(sql, &block)
408   else
409     execute_insert(sql)
410   end
411 end
last(*args, &block)

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}]
[show source]
    # File lib/sequel/dataset/actions.rb
423 def last(*args, &block)
424   raise(Error, 'No order specified') unless @opts[:order]
425   reverse.first(*args, &block)
426 end
map(column=nil, &block)

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'], ...]
[show source]
    # File lib/sequel/dataset/actions.rb
442 def map(column=nil, &block)
443   if column
444     raise(Error, 'Must call Dataset#map with either an argument or a block, not both') if block
445     return naked.map(column) if row_proc
446     if column.is_a?(Array)
447       super(){|r| r.values_at(*column)}
448     else
449       super(){|r| r[column]}
450     end
451   else
452     super(&block)
453   end
454 end
max(arg=(no_arg = true), &block)

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
[show source]
    # File lib/sequel/dataset/actions.rb
463 def max(arg=(no_arg = true), &block)
464   arg = Sequel.virtual_row(&block) if no_arg
465   _aggregate(:max, arg)
466 end
merge()

Execute a MERGE statement, which allows for INSERT, UPDATE, and DELETE behavior in a single query, based on whether rows from a source table match rows in the current table, based on the join conditions.

Unless the dataset uses static SQL, to use merge, you must first have called merge_using to specify the merge source and join conditions. You will then likely to call one or more of the following methods to specify MERGE behavior by adding WHEN [NOT] MATCHED clauses:

The WHEN [NOT] MATCHED clauses are added to the SQL in the order these methods were called on the dataset. If none of these methods are called, an error is raised.

Example:

DB[:m1]
  merge_using(:m2, i1: :i2).
  merge_insert(i1: :i2, a: Sequel[:b]+11).
  merge_delete{a > 30}.
  merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20).
  merge

SQL:

MERGE INTO m1 USING m2 ON (i1 = i2)
WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))
WHEN MATCHED AND (a > 30) THEN DELETE
WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

On PostgreSQL, two additional merge methods are supported, for the PostgreSQL-specific DO NOTHING syntax.

  • merge_do_nothing_when_matched

  • merge_do_nothing_when_not_matched

This method is supported on Oracle, but Oracle’s MERGE support is non-standard, and has the following issues:

  • DELETE clause requires UPDATE clause

  • DELETE clause requires a condition

  • DELETE clause only affects rows updated by UPDATE clause

[show source]
    # File lib/sequel/dataset/actions.rb
513 def merge
514   execute_ddl(merge_sql)
515 end
min(arg=(no_arg = true), &block)

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
[show source]
    # File lib/sequel/dataset/actions.rb
524 def min(arg=(no_arg = true), &block)
525   arg = Sequel.virtual_row(&block) if no_arg
526   _aggregate(:min, arg)
527 end
multi_insert(hashes, opts=OPTS)

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.

[show source]
    # File lib/sequel/dataset/actions.rb
541 def multi_insert(hashes, opts=OPTS)
542   return if hashes.empty?
543   columns = hashes.first.keys
544   import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
545 end
paged_each(opts=OPTS)

Yields each row in the dataset, but internally 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 retrieved 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
# ...
[show source]
    # File lib/sequel/dataset/actions.rb
602 def paged_each(opts=OPTS)
603   unless @opts[:order]
604     raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
605   end
606   unless defined?(yield)
607     return enum_for(:paged_each, opts)
608   end
609 
610   total_limit = @opts[:limit]
611   offset = @opts[:offset]
612   if server = @opts[:server]
613     opts = Hash[opts]
614     opts[:server] = server
615   end
616 
617   rows_per_fetch = opts[:rows_per_fetch] || 1000
618   strategy = if offset || total_limit
619     :offset
620   else
621     opts[:strategy] || :offset
622   end
623 
624   db.transaction(opts) do
625     case strategy
626     when :filter
627       filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
628       base_ds = ds = limit(rows_per_fetch)
629       while ds
630         last_row = nil
631         ds.each do |row|
632           last_row = row
633           yield row
634         end
635         ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
636       end
637     else
638       offset ||= 0
639       num_rows_yielded = rows_per_fetch
640       total_rows = 0
641 
642       while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
643         if total_limit && total_rows + rows_per_fetch > total_limit
644           rows_per_fetch = total_limit - total_rows
645         end
646 
647         num_rows_yielded = 0
648         limit(rows_per_fetch, offset).each do |row|
649           num_rows_yielded += 1
650           total_rows += 1 if total_limit
651           yield row
652         end
653 
654         offset += rows_per_fetch
655       end
656     end
657   end
658 
659   self
660 end
select_hash(key_column, value_column, opts = OPTS)

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 id, foo, name, bar 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.

[show source]
    # File lib/sequel/dataset/actions.rb
680 def select_hash(key_column, value_column, opts = OPTS)
681   _select_hash(:as_hash, key_column, value_column, opts)
682 end
select_hash_groups(key_column, value_column, opts = OPTS)

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 first, middle, last, id 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.

[show source]
    # File lib/sequel/dataset/actions.rb
701 def select_hash_groups(key_column, value_column, opts = OPTS)
702   _select_hash(:to_hash_groups, key_column, value_column, opts)
703 end
select_map(column=nil, &block)

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.

[show source]
    # File lib/sequel/dataset/actions.rb
724 def select_map(column=nil, &block)
725   _select_map(column, false, &block)
726 end
select_order_map(column=nil, &block)

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.

[show source]
    # File lib/sequel/dataset/actions.rb
743 def select_order_map(column=nil, &block)
744   _select_map(column, true, &block)
745 end
single_record()

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'}
[show source]
    # File lib/sequel/dataset/actions.rb
753 def single_record
754   _single_record_ds.single_record!
755 end
single_record!()

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'}
[show source]
    # File lib/sequel/dataset/actions.rb
765 def single_record!
766   with_sql_first(select_sql)
767 end
single_value()

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'
[show source]
    # File lib/sequel/dataset/actions.rb
775 def single_value
776   single_value_ds.each do |r|
777     r.each{|_, v| return v}
778   end
779   nil
780 end
single_value!()

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'
[show source]
    # File lib/sequel/dataset/actions.rb
790 def single_value!
791   with_sql_single_value(select_sql)
792 end
sum(arg=(no_arg = true), &block)

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
[show source]
    # File lib/sequel/dataset/actions.rb
801 def sum(arg=(no_arg = true), &block)
802   arg = Sequel.virtual_row(&block) if no_arg
803   _aggregate(:sum, arg)
804 end
to_hash(*a)

Alias of as_hash for backwards compatibility.

[show source]
    # File lib/sequel/dataset/actions.rb
858 def to_hash(*a)
859   as_hash(*a)
860 end
to_hash_groups(key_column, value_column = nil, opts = OPTS)

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.

[show source]
    # File lib/sequel/dataset/actions.rb
886 def to_hash_groups(key_column, value_column = nil, opts = OPTS)
887   h = opts[:hash] || {}
888   meth = opts[:all] ? :all : :each
889   if value_column
890     return naked.to_hash_groups(key_column, value_column, opts) if row_proc
891     if value_column.is_a?(Array)
892       if key_column.is_a?(Array)
893         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
894       else
895         public_send(meth){|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
896       end
897     else
898       if key_column.is_a?(Array)
899         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
900       else
901         public_send(meth){|r| (h[r[key_column]] ||= []) << r[value_column]}
902       end
903     end
904   elsif key_column.is_a?(Array)
905     public_send(meth){|r| (h[key_column.map{|k| r[k]}] ||= []) << r}
906   else
907     public_send(meth){|r| (h[r[key_column]] ||= []) << r}
908   end
909   h
910 end
truncate()

Truncates the dataset. Returns nil.

DB[:table].truncate # TRUNCATE table
# => nil
[show source]
    # File lib/sequel/dataset/actions.rb
916 def truncate
917   execute_ddl(truncate_sql)
918 end
update(values=OPTS, &block)

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
[show source]
    # File lib/sequel/dataset/actions.rb
929 def update(values=OPTS, &block)
930   sql = update_sql(values)
931   if uses_returning?(:update)
932     returning_fetch_rows(sql, &block)
933   else
934     execute_dui(sql)
935   end
936 end
where_all(cond, &block)

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))
[show source]
    # File lib/sequel/dataset/actions.rb
944 def where_all(cond, &block)
945   if loader = _where_loader([cond], nil)
946     loader.all(filter_expr(cond), &block)
947   else
948     where(cond).all(&block)
949   end
950 end
where_each(cond, &block)

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))
[show source]
    # File lib/sequel/dataset/actions.rb
958 def where_each(cond, &block)
959   if loader = _where_loader([cond], nil)
960     loader.each(filter_expr(cond), &block)
961   else
962     where(cond).each(&block)
963   end
964 end
where_single_value(cond)

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
[show source]
    # File lib/sequel/dataset/actions.rb
973 def where_single_value(cond)
974   if loader = cached_where_placeholder_literalizer([cond], nil, :_where_single_value_loader) do |pl|
975       single_value_ds.where(pl.arg)
976     end
977 
978     loader.get(filter_expr(cond))
979   else
980     where(cond).single_value
981   end
982 end
with_sql_all(sql, &block)

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.

[show source]
    # File lib/sequel/dataset/actions.rb
986 def with_sql_all(sql, &block)
987   _all(block){|a| with_sql_each(sql){|r| a << r}}
988 end
with_sql_delete(sql)

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.

[show source]
    # File lib/sequel/dataset/actions.rb
993 def with_sql_delete(sql)
994   execute_dui(sql)
995 end
with_sql_each(sql)

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

[show source]
     # File lib/sequel/dataset/actions.rb
 999 def with_sql_each(sql)
1000   if rp = row_proc
1001     _with_sql_dataset.fetch_rows(sql){|r| yield rp.call(r)}
1002   else
1003     _with_sql_dataset.fetch_rows(sql){|r| yield r}
1004   end
1005   self
1006 end
with_sql_first(sql)

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

[show source]
     # File lib/sequel/dataset/actions.rb
1010 def with_sql_first(sql)
1011   with_sql_each(sql){|r| return r}
1012   nil
1013 end
with_sql_insert(sql)

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

[show source]
     # File lib/sequel/dataset/actions.rb
1026 def with_sql_insert(sql)
1027   execute_insert(sql)
1028 end
with_sql_single_value(sql)

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.

[show source]
     # File lib/sequel/dataset/actions.rb
1018 def with_sql_single_value(sql)
1019   if r = with_sql_first(sql)
1020     r.each{|_, v| return v}
1021   end
1022 end

Protected Instance methods

_import(columns, values, opts)

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. A transaction is only used if there are multiple statements to execute.

[show source]
     # File lib/sequel/dataset/actions.rb
1036 def _import(columns, values, opts)
1037   trans_opts = Hash[opts]
1038   trans_opts[:server] = @opts[:server]
1039   if opts[:return] == :primary_key
1040     _import_transaction(values, trans_opts){values.map{|v| insert(columns, v)}}
1041   else
1042     stmts = multi_insert_sql(columns, values)
1043     _import_transaction(stmts, trans_opts){stmts.each{|st| execute_dui(st)}}
1044   end
1045 end
_select_map_multiple(ret_cols)

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

[show source]
     # File lib/sequel/dataset/actions.rb
1048 def _select_map_multiple(ret_cols)
1049   map{|r| r.values_at(*ret_cols)}
1050 end
_select_map_single()

Returns an array of the first value in each row.

[show source]
     # File lib/sequel/dataset/actions.rb
1053 def _select_map_single
1054   k = nil
1055   map{|r| r[k||=r.keys.first]}
1056 end
single_value_ds()

A dataset for returning single values from the current dataset.

[show source]
     # File lib/sequel/dataset/actions.rb
1059 def single_value_ds
1060   clone(:limit=>1).ungraphed.naked
1061 end

3 - User Methods relating to SQL Creation

Public Instance methods

exists()

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))
[show source]
   # File lib/sequel/dataset/sql.rb
14 def exists
15   SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
16 end
insert_sql(*values)

Returns an INSERT SQL query string. See insert.

DB[:items].insert_sql(a: 1)
# => "INSERT INTO items (a) VALUES (1)"
[show source]
   # File lib/sequel/dataset/sql.rb
22 def insert_sql(*values)
23   return static_sql(@opts[:sql]) if @opts[:sql]
24 
25   check_insert_allowed!
26 
27   columns, values = _parse_insert_sql_args(values)
28   if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
29     columns, values = insert_empty_columns_values
30   elsif values.is_a?(Dataset) && hoist_cte?(values) && supports_cte?(:insert)
31     ds, values = hoist_cte(values)
32     return ds.clone(:columns=>columns, :values=>values).send(:_insert_sql)
33   end
34   clone(:columns=>columns, :values=>values).send(:_insert_sql)
35 end
literal_append(sql, v)

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

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

[show source]
   # File lib/sequel/dataset/sql.rb
40 def literal_append(sql, v)
41   case v
42   when Symbol
43     if skip_symbol_cache?
44       literal_symbol_append(sql, v)
45     else 
46       unless l = db.literal_symbol(v)
47         l = String.new
48         literal_symbol_append(l, v)
49         db.literal_symbol_set(v, l)
50       end
51       sql << l
52     end
53   when String
54     case v
55     when LiteralString
56       sql << v
57     when SQL::Blob
58       literal_blob_append(sql, v)
59     else
60       literal_string_append(sql, v)
61     end
62   when Integer
63     sql << literal_integer(v)
64   when Hash
65     literal_hash_append(sql, v)
66   when SQL::Expression
67     literal_expression_append(sql, v)
68   when Float
69     sql << literal_float(v)
70   when BigDecimal
71     sql << literal_big_decimal(v)
72   when NilClass
73     sql << literal_nil
74   when TrueClass
75     sql << literal_true
76   when FalseClass
77     sql << literal_false
78   when Array
79     literal_array_append(sql, v)
80   when Time
81     v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v)
82   when DateTime
83     literal_datetime_append(sql, v)
84   when Date
85     sql << literal_date(v)
86   when Dataset
87     literal_dataset_append(sql, v)
88   else
89     literal_other_append(sql, v)
90   end
91 end
merge_sql()

The SQL to use for the MERGE statement.

[show source]
    # File lib/sequel/dataset/sql.rb
 94 def merge_sql
 95   raise Error, "This database doesn't support MERGE" unless supports_merge?
 96   if sql = opts[:sql]
 97     return static_sql(sql)
 98   end
 99   if sql = cache_get(:_merge_sql)
100     return sql
101   end
102   source, join_condition = @opts[:merge_using]
103   raise Error, "No USING clause for MERGE" unless source
104   sql = @opts[:append_sql] || sql_string_origin
105 
106   select_with_sql(sql)
107   sql << "MERGE INTO "
108   source_list_append(sql, @opts[:from])
109   sql << " USING "
110   identifier_append(sql, source)
111   sql << " ON "
112   literal_append(sql, join_condition)
113   _merge_when_sql(sql)
114   cache_set(:_merge_sql, sql) if cache_sql?
115   sql
116 end
multi_insert_sql(columns, values)

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.

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

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

[show source]
    # File lib/sequel/dataset/sql.rb
149 def sql
150   select_sql
151 end
truncate_sql()

Returns a TRUNCATE SQL query string. See truncate

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

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.

[show source]
    # File lib/sequel/dataset/sql.rb
176 def update_sql(values = OPTS)
177   return static_sql(opts[:sql]) if opts[:sql]
178   check_update_allowed!
179   check_not_limited!(:update)
180 
181   case values
182   when LiteralString
183     # nothing
184   when String
185     raise Error, "plain string passed to Dataset#update is not supported, use Sequel.lit to use a literal string"
186   end
187 
188   clone(:values=>values).send(:_update_sql)
189 end

4 - Methods that describe what the dataset supports

Public Instance methods

provides_accurate_rows_matched?()

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.

[show source]
   # File lib/sequel/dataset/features.rb
19 def provides_accurate_rows_matched?
20   true
21 end
quote_identifiers?()

Whether this dataset quotes identifiers.

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

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

[show source]
   # File lib/sequel/dataset/features.rb
24 def recursive_cte_requires_column_aliases?
25   false
26 end
requires_placeholder_type_specifiers?()

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

[show source]
   # File lib/sequel/dataset/features.rb
36 def requires_placeholder_type_specifiers?
37   false
38 end
requires_sql_standard_datetimes?()

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

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

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.

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

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.

[show source]
   # File lib/sequel/dataset/features.rb
50 def supports_cte_in_subqueries?
51   false
52 end
supports_deleting_joins?()

Whether deleting from joined datasets is supported, false by default.

[show source]
   # File lib/sequel/dataset/features.rb
55 def supports_deleting_joins?
56   supports_modifying_joins?
57 end
supports_derived_column_lists?()

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

[show source]
   # File lib/sequel/dataset/features.rb
62 def supports_derived_column_lists?
63   true
64 end
supports_distinct_on?()

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

[show source]
   # File lib/sequel/dataset/features.rb
67 def supports_distinct_on?
68   false
69 end
supports_group_cube?()

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

[show source]
   # File lib/sequel/dataset/features.rb
72 def supports_group_cube?
73   false
74 end
supports_group_rollup?()

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

[show source]
   # File lib/sequel/dataset/features.rb
77 def supports_group_rollup?
78   false
79 end
supports_grouping_sets?()

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

[show source]
   # File lib/sequel/dataset/features.rb
82 def supports_grouping_sets?
83   false
84 end
supports_insert_select?()

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

[show source]
   # File lib/sequel/dataset/features.rb
88 def supports_insert_select?
89   supports_returning?(:insert)
90 end
supports_intersect_except?()

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

[show source]
   # File lib/sequel/dataset/features.rb
93 def supports_intersect_except?
94   true
95 end
supports_intersect_except_all?()

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

[show source]
    # File lib/sequel/dataset/features.rb
 98 def supports_intersect_except_all?
 99   true
100 end
supports_is_true?()

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

[show source]
    # File lib/sequel/dataset/features.rb
103 def supports_is_true?
104   true
105 end
supports_join_using?()

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).

[show source]
    # File lib/sequel/dataset/features.rb
109 def supports_join_using?
110   true
111 end
supports_lateral_subqueries?()

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

[show source]
    # File lib/sequel/dataset/features.rb
114 def supports_lateral_subqueries?
115   false
116 end
supports_limits_in_correlated_subqueries?()

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

[show source]
    # File lib/sequel/dataset/features.rb
119 def supports_limits_in_correlated_subqueries?
120   true
121 end
supports_merge?()

Whether the MERGE statement is supported, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
129 def supports_merge?
130   false
131 end
supports_modifying_joins?()

Whether modifying joined datasets is supported, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
134 def supports_modifying_joins?
135   false
136 end
supports_multiple_column_in?()

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

[show source]
    # File lib/sequel/dataset/features.rb
140 def supports_multiple_column_in?
141   true
142 end
supports_nowait?()

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

[show source]
    # File lib/sequel/dataset/features.rb
124 def supports_nowait?
125   false
126 end
supports_offsets_in_correlated_subqueries?()

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

[show source]
    # File lib/sequel/dataset/features.rb
145 def supports_offsets_in_correlated_subqueries?
146   true
147 end
supports_ordered_distinct_on?()

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

[show source]
    # File lib/sequel/dataset/features.rb
151 def supports_ordered_distinct_on?
152   supports_distinct_on?
153 end
supports_placeholder_literalizer?()

Whether placeholder literalizers are supported, true by default.

[show source]
    # File lib/sequel/dataset/features.rb
156 def supports_placeholder_literalizer?
157   true
158 end
supports_regexp?()

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

[show source]
    # File lib/sequel/dataset/features.rb
161 def supports_regexp?
162   false
163 end
supports_replace?()

Whether the dataset supports REPLACE syntax, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
166 def supports_replace?
167   false
168 end
supports_returning?(type)

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

[show source]
    # File lib/sequel/dataset/features.rb
172 def supports_returning?(type)
173   false
174 end
supports_select_all_and_column?()

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

[show source]
    # File lib/sequel/dataset/features.rb
182 def supports_select_all_and_column?
183   true
184 end
supports_skip_locked?()

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

[show source]
    # File lib/sequel/dataset/features.rb
177 def supports_skip_locked?
178   false
179 end
supports_timestamp_timezones?()

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

[show source]
    # File lib/sequel/dataset/features.rb
187 def supports_timestamp_timezones?
188   false
189 end
supports_timestamp_usecs?()

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

[show source]
    # File lib/sequel/dataset/features.rb
192 def supports_timestamp_usecs?
193   true
194 end
supports_updating_joins?()

Whether updating joined datasets is supported, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
197 def supports_updating_joins?
198   supports_modifying_joins?
199 end
supports_where_true?()

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

[show source]
    # File lib/sequel/dataset/features.rb
226 def supports_where_true?
227   true
228 end
supports_window_clause?()

Whether the dataset supports the WINDOW clause to define windows used by multiple window functions, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
203 def supports_window_clause?
204   false
205 end
supports_window_function_frame_option?(option)

Whether the dataset supports the given window function option. True by default. This should only be called if supports_window_functions? is true. Possible options are :rows, :range, :groups, :offset, :exclude.

[show source]
    # File lib/sequel/dataset/features.rb
215 def supports_window_function_frame_option?(option)
216   case option
217   when :rows, :range, :offset
218     true
219   else
220     false
221   end
222 end
supports_window_functions?()

Whether the dataset supports window functions, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
208 def supports_window_functions?
209   false
210 end

5 - Methods related to dataset graphing

Public Instance methods

add_graph_aliases(graph_aliases)

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
[show source]
   # 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 => graph.merge(:column_aliases=>ga.merge(graph_aliases).freeze).freeze)
25 end
graph(dataset, join_conditions = nil, options = OPTS, &block)

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.

[show source]
    # 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   joined_dataset = joined_dataset?
100   ds = self
101   graph = opts[:graph]
102 
103   if !graph && (select = @opts[:select]) && !select.empty?
104     select_columns = nil
105 
106     unless !joined_dataset && select.length == 1 && (select[0].is_a?(SQL::ColumnAll))
107       force_from_self = false
108       select_columns = select.map do |sel|
109         unless col = _hash_key_symbol(sel)
110           force_from_self = true
111           break
112         end
113 
114         [sel, col]
115       end
116 
117       select_columns = nil if force_from_self
118     end
119   end
120 
121   # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs)
122   if (@opts[:graph_from_self] != false && !graph && (joined_dataset || force_from_self))
123     from_selfed = true
124     implicit_qualifier = options[:from_self_alias] || first_source
125     ds = ds.from_self(:alias=>implicit_qualifier)
126   end
127   
128   # Join the table early in order to avoid cloning the dataset twice
129   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)
130 
131   return ds if options[:join_only]
132 
133   opts = ds.opts
134 
135   # Whether to include the table in the result set
136   add_table = options[:select] == false ? false : true
137 
138   if graph
139     graph = graph.dup
140     select = opts[:select].dup
141     [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
142   else
143     # Setup the initial graph data structure if it doesn't exist
144     qualifier = ds.first_source_alias
145     master = alias_symbol(qualifier)
146     raise_alias_error.call if master == table_alias
147 
148     # Master hash storing all .graph related information
149     graph = {}
150 
151     # Associates column aliases back to tables and columns
152     column_aliases = graph[:column_aliases] = {}
153 
154     # Associates table alias (the master is never aliased)
155     table_aliases = graph[:table_aliases] = {master=>self}
156 
157     # Keep track of the alias numbers used
158     ca_num = graph[:column_alias_num] = Hash.new(0)
159 
160     select = if select_columns
161       select_columns.map do |sel, column|
162         column_aliases[column] = [master, column]
163         if from_selfed
164           # Initial dataset was wrapped in subselect, selected all
165           # columns in the subselect, qualified by the subselect alias.
166           Sequel.qualify(qualifier, Sequel.identifier(column))
167         else
168           # Initial dataset not wrapped in subslect, just make
169           # sure columns are qualified in some way.
170           qualified_expression(sel, qualifier)
171         end
172       end
173     else
174       columns.map do |column|
175         column_aliases[column] = [master, column]
176         SQL::QualifiedIdentifier.new(qualifier, column)
177       end
178     end
179   end
180 
181   # Add the table alias to the list of aliases
182   # Even if it isn't been used in the result set,
183   # we add a key for it with a nil value so we can check if it
184   # is used more than once
185   table_aliases = graph[:table_aliases]
186   table_aliases[table_alias] = add_table ? dataset : nil
187 
188   # Add the columns to the selection unless we are ignoring them
189   if add_table
190     column_aliases = graph[:column_aliases]
191     ca_num = graph[:column_alias_num]
192     # Which columns to add to the result set
193     cols = options[:select] || dataset.columns
194     # If the column hasn't been used yet, don't alias it.
195     # If it has been used, try table_column.
196     # If that has been used, try table_column_N
197     # using the next value of N that we know hasn't been
198     # used
199     cols.each do |column|
200       col_alias, identifier = if column_aliases[column]
201         column_alias = :"#{table_alias}_#{column}"
202         if column_aliases[column_alias]
203           column_alias_num = ca_num[column_alias]
204           column_alias = :"#{column_alias}_#{column_alias_num}" 
205           ca_num[column_alias] += 1
206         end
207         [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)]
208       else
209         ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column)
210         [column, ident]
211       end
212       column_aliases[col_alias] = [table_alias, column].freeze
213       select.push(identifier)
214     end
215   end
216   [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k].freeze}
217   ds = ds.clone(:graph=>graph.freeze)
218   ds.select(*select)
219 end
set_graph_aliases(graph_aliases)

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 ...
[show source]
    # File lib/sequel/dataset/graph.rb
244 def set_graph_aliases(graph_aliases)
245   columns, graph_aliases = graph_alias_columns(graph_aliases)
246   if graph = opts[:graph]
247     select(*columns).clone(:graph => graph.merge(:column_aliases=>graph_aliases.freeze).freeze)
248   else
249     raise Error, "cannot call #set_graph_aliases on an ungraphed dataset"
250   end
251 end
ungraphed()

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

[show source]
    # File lib/sequel/dataset/graph.rb
255 def ungraphed
256   clone(:graph=>nil)
257 end

6 - Miscellaneous methods

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)

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.

[show source]
   # 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)

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

[show source]
   # 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()

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

[show source]
   # File lib/sequel/dataset/misc.rb
40 def current_datetime
41   Sequel.datetime_class.now
42 end
dup()

Return self, as datasets are always frozen.

[show source]
   # File lib/sequel/dataset/misc.rb
50 def dup
51   self
52 end
each_server()

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')}
[show source]
   # File lib/sequel/dataset/misc.rb
59 def each_server
60   db.servers.each{|s| yield server(s)}
61 end
eql?(o)

Alias for ==

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

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

Alias of first_source_alias

[show source]
   # File lib/sequel/dataset/misc.rb
91 def first_source
92   first_source_alias
93 end
first_source_alias()

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
[show source]
    # 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()

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
[show source]
    # 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()

Freeze the opts when freezing the dataset.

[show source]
   # File lib/sequel/dataset/misc.rb
74 def freeze
75   @opts.freeze
76   super
77 end
hash()

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

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

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

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

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

[show source]
    # 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()

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

[show source]
    # File lib/sequel/dataset/misc.rb
163 def row_number_column
164   :x_sequel_row_number_x
165 end
row_proc()

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.

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

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.

[show source]
    # 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)

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.

[show source]
    # 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 = [])

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
[show source]
    # 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)

Return a modified dataset with quote_identifiers set.

[show source]
    # 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()

The cached columns for the current dataset.

[show source]
    # File lib/sequel/dataset/misc.rb
271 def _columns
272   cache_get(:_columns)
273 end
cache_get(k)

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

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

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

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

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).

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

8 - Methods related to prepared statements or bound variables

Constants

DEFAULT_PREPARED_STATEMENT_MODULE_METHODS = %w'execute execute_dui execute_insert'.freeze.each(&:freeze)  
PREPARED_ARG_PLACEHOLDER = LiteralString.new('?').freeze  
PREPARED_STATEMENT_MODULE_CODE = { :bind => "opts = Hash[opts]; opts[:arguments] = bind_arguments".freeze, :prepare => "sql = prepared_statement_name".freeze, :prepare_bind => "sql = prepared_statement_name; opts = Hash[opts]; opts[:arguments] = bind_arguments".freeze }.freeze  

Public Instance methods

bind(bind_vars=OPTS)

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}
[show source]
    # File lib/sequel/dataset/prepared_statements.rb
332 def bind(bind_vars=OPTS)
333   bind_vars = if bv = @opts[:bind_vars]
334     bv.merge(bind_vars).freeze
335   else
336     if bind_vars.frozen?
337       bind_vars
338     else
339       Hash[bind_vars]
340     end
341   end
342 
343   clone(:bind_vars=>bind_vars)
344 end
call(type, bind_variables=OPTS, *values, &block)

For the given type (:select, :first, :insert, :insert_select, :update, :delete, or :single_value), 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}
[show source]
    # File lib/sequel/dataset/prepared_statements.rb
353 def call(type, bind_variables=OPTS, *values, &block)
354   to_prepared_statement(type, values, :extend=>bound_variable_modules).call(bind_variables, &block)
355 end
prepare(type, name, *values)

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
[show source]
    # File lib/sequel/dataset/prepared_statements.rb
373 def prepare(type, name, *values)
374   ps = to_prepared_statement(type, values, :name=>name, :extend=>prepared_statement_modules, :no_delayed_evaluations=>true)
375 
376   ps = if ps.send(:emulate_prepared_statements?)
377     ps = ps.with_extend(EmulatePreparedStatementMethods)
378     ps.send(:emulated_prepared_statement, type, name, values)
379   else
380     sql = ps.prepared_sql
381     ps.prepared_args.freeze
382     ps.clone(:prepared_sql=>sql, :sql=>sql)
383   end
384 
385   db.set_prepared_statement(name, ps)
386   ps
387 end

Protected Instance methods

to_prepared_statement(type, values=nil, opts=OPTS)

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

[show source]
    # File lib/sequel/dataset/prepared_statements.rb
393 def to_prepared_statement(type, values=nil, opts=OPTS)
394   mods = opts[:extend] || []
395   mods += [PreparedStatementMethods]
396 
397   bind.
398     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]).
399     with_extend(*mods)
400 end

9 - Internal Methods relating to SQL Creation

Constants

BITWISE_METHOD_MAP = {:& =>:BITAND, :| => :BITOR, :^ => :BITXOR}.freeze  
COUNT_FROM_SELF_OPTS = [:distinct, :group, :sql, :limit, :offset, :compounds].freeze  
COUNT_OF_ALL_AS_COUNT = SQL::Function.new(:count, WILDCARD).as(:count)  
DEFAULT = LiteralString.new('DEFAULT').freeze  
EXISTS = ['EXISTS '.freeze].freeze  
IS_LITERALS = {nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze  
IS_OPERATORS = ::Sequel::SQL::ComplexExpression::IS_OPERATORS  
LIKE_OPERATORS = ::Sequel::SQL::ComplexExpression::LIKE_OPERATORS  
N_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS  
QUALIFY_KEYS = [:select, :where, :having, :order, :group].freeze  
REGEXP_OPERATORS = ::Sequel::SQL::ComplexExpression::REGEXP_OPERATORS  
TWO_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS  
WILDCARD = LiteralString.new('*').freeze  

Public Class methods

clause_methods(type, clauses)

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

[show source]
    # File lib/sequel/dataset/sql.rb
198 def self.clause_methods(type, clauses)
199   clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
200 end
def_sql_method(mod, type, clauses)

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.

[show source]
    # File lib/sequel/dataset/sql.rb
212 def self.def_sql_method(mod, type, clauses)
213   priv = type == :update || type == :insert
214   cacheable = type == :select || type == :delete
215 
216   lines = []
217   lines << 'private' if priv
218   lines << "def #{'_' if priv}#{type}_sql"
219   lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
220   lines << "if sql = cache_get(:_#{type}_sql); return sql end" if cacheable
221   lines << 'check_delete_allowed!' << 'check_not_limited!(:delete)' if type == :delete
222   lines << 'sql = @opts[:append_sql] || sql_string_origin'
223 
224   if clauses.all?{|c| c.is_a?(Array)}
225     clauses.each do |i, cs|
226       lines << i
227       lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 
228     end 
229     lines << 'end'
230   else
231     lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
232   end
233 
234   lines << "cache_set(:_#{type}_sql, sql) if cache_sql?" if cacheable
235   lines << 'sql'
236   lines << 'end'
237 
238   mod.class_eval lines.join("\n"), __FILE__, __LINE__
239 end

Public Instance methods

aliased_expression_sql_append(sql, ae)

Append literalization of aliased expression to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
273 def aliased_expression_sql_append(sql, ae)
274   literal_append(sql, ae.expression)
275   as_sql_append(sql, ae.alias, ae.columns)
276 end
array_sql_append(sql, a)

Append literalization of array to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
279 def array_sql_append(sql, a)
280   if a.empty?
281     sql << '(NULL)'
282   else
283     sql << '('
284     expression_list_append(sql, a)
285     sql << ')'
286   end
287 end
boolean_constant_sql_append(sql, constant)

Append literalization of boolean constant to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
290 def boolean_constant_sql_append(sql, constant)
291   if (constant == true || constant == false) && !supports_where_true?
292     sql << (constant == true ? '(1 = 1)' : '(1 = 0)')
293   else
294     literal_append(sql, constant)
295   end
296 end
case_expression_sql_append(sql, ce)

Append literalization of case expression to SQL string.

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

Append literalization of cast expression to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
319 def cast_sql_append(sql, expr, type)
320   sql << 'CAST('
321   literal_append(sql, expr)
322   sql << ' AS ' << db.cast_type_literal(type).to_s
323   sql << ')'
324 end
column_all_sql_append(sql, ca)

Append literalization of column all selection to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
327 def column_all_sql_append(sql, ca)
328   qualified_identifier_sql_append(sql, ca.table, WILDCARD)
329 end
complex_expression_sql_append(sql, op, args)

Append literalization of complex expression to SQL string.

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

Append literalization of constant to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
441 def constant_sql_append(sql, constant)
442   sql << constant.to_s
443 end
delayed_evaluation_sql_append(sql, delay)

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

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

Append literalization of function call to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
461 def function_sql_append(sql, f)
462   name = f.name
463   opts = f.opts
464 
465   if opts[:emulate]
466     if emulate_function?(name)
467       emulate_function_sql_append(sql, f)
468       return
469     end
470 
471     name = native_function_name(name) 
472   end
473 
474   sql << 'LATERAL ' if opts[:lateral]
475 
476   case name
477   when SQL::Identifier
478     if supports_quoted_function_names? && opts[:quoted]
479       literal_append(sql, name)
480     else
481       sql << name.value.to_s
482     end
483   when SQL::QualifiedIdentifier
484     if supports_quoted_function_names? && opts[:quoted] != false
485       literal_append(sql, name)
486     else
487       sql << split_qualifiers(name).join('.')
488     end
489   else
490     if supports_quoted_function_names? && opts[:quoted]
491       quote_identifier_append(sql, name)
492     else
493       sql << name.to_s
494     end
495   end
496 
497   sql << '('
498   if filter = opts[:filter]
499     filter = filter_expr(filter, &opts[:filter_block])
500   end
501   if opts[:*]
502     if filter && !supports_filtered_aggregates?
503       literal_append(sql, Sequel.case({filter=>1}, nil))
504       filter = nil
505     else
506       sql <<  '*'
507     end
508   else
509     sql << "DISTINCT " if opts[:distinct]
510     if filter && !supports_filtered_aggregates?
511       expression_list_append(sql, f.args.map{|arg| Sequel.case({filter=>arg}, nil)})
512       filter = nil
513     else
514       expression_list_append(sql, f.args)
515     end
516     if order = opts[:order]
517       sql << " ORDER BY "
518       expression_list_append(sql, order)
519     end
520   end
521   sql << ')'
522 
523   if group = opts[:within_group]
524     sql << " WITHIN GROUP (ORDER BY "
525     expression_list_append(sql, group)
526     sql << ')'
527   end
528 
529   if filter
530     sql << " FILTER (WHERE "
531     literal_append(sql, filter)
532     sql << ')'
533   end
534 
535   if window = opts[:over]
536     sql << ' OVER '
537     window_sql_append(sql, window.opts)
538   end
539 
540   if opts[:with_ordinality]
541     sql << " WITH ORDINALITY"
542   end
543 end
join_clause_sql_append(sql, jc)

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

[show source]
    # File lib/sequel/dataset/sql.rb
546 def join_clause_sql_append(sql, jc)
547   table = jc.table
548   table_alias = jc.table_alias
549   table_alias = nil if table == table_alias && !jc.column_aliases
550   sql << ' ' << join_type_sql(jc.join_type) << ' '
551   identifier_append(sql, table)
552   as_sql_append(sql, table_alias, jc.column_aliases) if table_alias
553 end
join_on_clause_sql_append(sql, jc)

Append literalization of JOIN ON clause to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
556 def join_on_clause_sql_append(sql, jc)
557   join_clause_sql_append(sql, jc)
558   sql << ' ON '
559   literal_append(sql, filter_expr(jc.on))
560 end
join_using_clause_sql_append(sql, jc)

Append literalization of JOIN USING clause to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
563 def join_using_clause_sql_append(sql, jc)
564   join_clause_sql_append(sql, jc)
565   join_using_clause_using_sql_append(sql, jc.using) 
566 end
negative_boolean_constant_sql_append(sql, constant)

Append literalization of negative boolean constant to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
569 def negative_boolean_constant_sql_append(sql, constant)
570   sql << 'NOT '
571   boolean_constant_sql_append(sql, constant)
572 end
ordered_expression_sql_append(sql, oe)

Append literalization of ordered expression to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
575 def ordered_expression_sql_append(sql, oe)
576   if emulate = requires_emulating_nulls_first?
577     case oe.nulls
578     when :first
579       null_order = 0
580     when :last
581       null_order = 2
582     end
583 
584     if null_order
585       literal_append(sql, Sequel.case({{oe.expression=>nil}=>null_order}, 1))
586       sql << ", "
587     end
588   end
589 
590   literal_append(sql, oe.expression)
591   sql << (oe.descending ? ' DESC' : ' ASC')
592 
593   unless emulate
594     case oe.nulls
595     when :first
596       sql << " NULLS FIRST"
597     when :last
598       sql << " NULLS LAST"
599     end
600   end
601 end
placeholder_literal_string_sql_append(sql, pls)

Append literalization of placeholder literal string to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
604 def placeholder_literal_string_sql_append(sql, pls)
605   args = pls.args
606   str = pls.str
607   sql << '(' if pls.parens
608   if args.is_a?(Hash)
609     if args.empty?
610       sql << str
611     else
612       re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
613       while true
614         previous, q, str = str.partition(re)
615         sql << previous
616         literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
617         break if str.empty?
618       end
619     end
620   elsif str.is_a?(Array)
621     len = args.length
622     str.each_with_index do |s, i|
623       sql << s
624       literal_append(sql, args[i]) unless i == len
625     end
626     unless str.length == args.length || str.length == args.length + 1
627       raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
628     end
629   else
630     i = -1
631     match_len = args.length - 1
632     while true
633       previous, q, str = str.partition('?')
634       sql << previous
635       literal_append(sql, args.at(i+=1)) unless q.empty?
636       if str.empty?
637         unless i == match_len
638           raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder string"
639         end
640         break
641       end
642     end
643   end
644   sql << ')' if pls.parens
645 end
qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))

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.

[show source]
    # File lib/sequel/dataset/sql.rb
650 def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
651   identifier_append(sql, table)
652   sql << '.'
653   identifier_append(sql, column)
654 end
quote_identifier_append(sql, name)

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.

[show source]
    # File lib/sequel/dataset/sql.rb
660 def quote_identifier_append(sql, name)
661   if name.is_a?(LiteralString)
662     sql << name
663   else
664     name = name.value if name.is_a?(SQL::Identifier)
665     name = input_identifier(name)
666     if quote_identifiers?
667       quoted_identifier_append(sql, name)
668     else
669       sql << name
670     end
671   end
672 end
quote_schema_table_append(sql, table)

Append literalization of identifier or unqualified identifier to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
675 def quote_schema_table_append(sql, table)
676   schema, table = schema_and_table(table)
677   if schema
678     quote_identifier_append(sql, schema)
679     sql << '.'
680   end
681   quote_identifier_append(sql, table)
682 end
quoted_identifier_append(sql, name)

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).

[show source]
    # File lib/sequel/dataset/sql.rb
688 def quoted_identifier_append(sql, name)
689   sql << '"' << name.to_s.gsub('"', '""') << '"'
690 end
schema_and_table(table_name, sch=nil)

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).

[show source]
    # File lib/sequel/dataset/sql.rb
699 def schema_and_table(table_name, sch=nil)
700   sch = sch.to_s if sch
701   case table_name
702   when Symbol
703     s, t, _ = split_symbol(table_name)
704     [s||sch, t]
705   when SQL::QualifiedIdentifier
706     [table_name.table.to_s, table_name.column.to_s]
707   when SQL::Identifier
708     [sch, table_name.value.to_s]
709   when String
710     [sch, table_name]
711   else
712     raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
713   end
714 end
split_qualifiers(table_name, *args)

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']
[show source]
    # File lib/sequel/dataset/sql.rb
722 def split_qualifiers(table_name, *args)
723   case table_name
724   when SQL::QualifiedIdentifier
725     split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
726   else
727     sch, table = schema_and_table(table_name, *args)
728     sch ? [sch, table] : [table]
729   end
730 end
subscript_sql_append(sql, s)

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

[show source]
    # File lib/sequel/dataset/sql.rb
733 def subscript_sql_append(sql, s)
734   case s.expression
735   when Symbol, SQL::Subscript, SQL::Identifier, SQL::QualifiedIdentifier
736     # nothing
737   else
738     wrap_expression = true
739     sql << '('
740   end
741   literal_append(sql, s.expression)
742   if wrap_expression
743     sql << ')['
744   else
745     sql << '['
746   end
747   sub = s.sub
748   if sub.length == 1 && (range = sub.first).is_a?(Range)
749     literal_append(sql, range.begin)
750     sql << ':'
751     e = range.end
752     e -= 1 if range.exclude_end? && e.is_a?(Integer)
753     literal_append(sql, e)
754   else
755     expression_list_append(sql, s.sub)
756   end
757   sql << ']'
758 end
window_sql_append(sql, opts)

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

[show source]
    # File lib/sequel/dataset/sql.rb
761 def window_sql_append(sql, opts)
762   raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
763   space = false
764   space_s = ' '
765 
766   sql << '('
767 
768   if window = opts[:window]
769     literal_append(sql, window)
770     space = true
771   end
772 
773   if part = opts[:partition]
774     sql << space_s if space
775     sql << "PARTITION BY "
776     expression_list_append(sql, Array(part))
777     space = true
778   end
779 
780   if order = opts[:order]
781     sql << space_s if space
782     sql << "ORDER BY "
783     expression_list_append(sql, Array(order))
784     space = true
785   end
786 
787   if frame = opts[:frame]
788     sql << space_s if space
789 
790     if frame.is_a?(String)
791       sql << frame
792     else
793       case frame
794       when :all
795         frame_type = :rows
796         frame_start = :preceding
797         frame_end = :following
798       when :rows, :range, :groups
799         frame_type = frame
800         frame_start = :preceding
801         frame_end = :current
802       when Hash
803         frame_type = frame[:type]
804         unless frame_type == :rows || frame_type == :range || frame_type == :groups
805           raise Error, "invalid window :frame :type option: #{frame_type.inspect}"
806         end
807         unless frame_start = frame[:start]
808           raise Error, "invalid window :frame :start option: #{frame_start.inspect}"
809         end
810         frame_end = frame[:end]
811         frame_exclude = frame[:exclude]
812       else
813         raise Error, "invalid window :frame option: #{frame.inspect}"
814       end
815 
816       sql << frame_type.to_s.upcase << " "
817       sql << 'BETWEEN ' if frame_end
818       window_frame_boundary_sql_append(sql, frame_start, :preceding)
819       if frame_end
820         sql << " AND "
821         window_frame_boundary_sql_append(sql, frame_end, :following)
822       end
823 
824       if frame_exclude
825         sql << " EXCLUDE "
826 
827         case frame_exclude
828         when :current
829           sql << "CURRENT ROW"
830         when :group
831           sql << "GROUP"
832         when :ties
833           sql << "TIES"
834         when :no_others
835           sql << "NO OTHERS"
836         else
837           raise Error, "invalid window :frame :exclude option: #{frame_exclude.inspect}"
838         end
839       end
840     end
841   end
842 
843   sql << ')'
844 end

Protected Instance methods

compound_from_self()

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

[show source]
    # File lib/sequel/dataset/sql.rb
850 def compound_from_self
851   (@opts[:sql] || @opts[:limit] || @opts[:order] || @opts[:offset]) ? from_self : self
852 end