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. min
  81. multi_insert
  82. multi_insert_sql
  83. naked
  84. negative_boolean_constant_sql_append
  85. nowait
  86. offset
  87. opts
  88. or
  89. order
  90. order_append
  91. order_by
  92. order_more
  93. order_prepend
  94. ordered_expression_sql_append
  95. paged_each
  96. placeholder_literal_string_sql_append
  97. prepare
  98. provides_accurate_rows_matched?
  99. qualified_identifier_sql_append
  100. qualify
  101. quote_identifier_append
  102. quote_identifiers?
  103. quote_schema_table_append
  104. quoted_identifier_append
  105. recursive_cte_requires_column_aliases?
  106. requires_placeholder_type_specifiers?
  107. requires_sql_standard_datetimes?
  108. returning
  109. reverse
  110. reverse_order
  111. row_number_column
  112. row_proc
  113. schema_and_table
  114. select
  115. select_all
  116. select_append
  117. select_group
  118. select_hash
  119. select_hash_groups
  120. select_map
  121. select_more
  122. select_order_map
  123. server
  124. server?
  125. set_graph_aliases
  126. single_record
  127. single_record!
  128. single_value
  129. single_value!
  130. skip_limit_check
  131. skip_locked
  132. split_alias
  133. split_qualifiers
  134. sql
  135. subscript_sql_append
  136. sum
  137. supports_cte?
  138. supports_cte_in_subqueries?
  139. supports_derived_column_lists?
  140. supports_distinct_on?
  141. supports_group_cube?
  142. supports_group_rollup?
  143. supports_grouping_sets?
  144. supports_insert_select?
  145. supports_intersect_except?
  146. supports_intersect_except_all?
  147. supports_is_true?
  148. supports_join_using?
  149. supports_lateral_subqueries?
  150. supports_limits_in_correlated_subqueries?
  151. supports_modifying_joins?
  152. supports_multiple_column_in?
  153. supports_nowait?
  154. supports_offsets_in_correlated_subqueries?
  155. supports_ordered_distinct_on?
  156. supports_regexp?
  157. supports_replace?
  158. supports_returning?
  159. supports_select_all_and_column?
  160. supports_skip_locked?
  161. supports_timestamp_timezones?
  162. supports_timestamp_usecs?
  163. supports_where_true?
  164. supports_window_clause?
  165. supports_window_function_frame_option?
  166. supports_window_functions?
  167. to_hash
  168. to_hash_groups
  169. truncate
  170. truncate_sql
  171. unfiltered
  172. ungraphed
  173. ungrouped
  174. union
  175. unlimited
  176. unordered
  177. unqualified_column_for
  178. unused_table_alias
  179. update
  180. update_sql
  181. where
  182. where_all
  183. where_each
  184. where_single_value
  185. window
  186. window_sql_append
  187. with
  188. with_extend
  189. with_quote_identifiers
  190. with_recursive
  191. with_row_proc
  192. with_sql
  193. with_sql_all
  194. with_sql_delete
  195. with_sql_each
  196. with_sql_first
  197. with_sql_insert
  198. 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 = (return self; nil))

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 = (return self; nil))
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 emualting the DISTINCT ON support in MySQL, but it does not support the ORDER of the dataset, and also doesn't work in many cases if the ONLY_FULL_GROUP_BY sql_mode is used, which is the default on MySQL 5.7.5+.

[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   if opts[:all_patterns]
334     conds = Array(patterns).map do |pat|
335       SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
336     end
337     where(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds))
338   else
339     conds = Array(columns).map do |c|
340       SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
341     end
342     where(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds))
343   end
344 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
353 def group(*columns, &block)
354   virtual_row_columns(columns, block)
355   clone(:group => (columns.compact.empty? ? nil : columns.freeze))
356 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
384 def group_and_count(*columns, &block)
385   select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT)
386 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
394 def group_append(*columns, &block)
395   columns = @opts[:group] + columns if @opts[:group]
396   group(*columns, &block)
397 end
group_by (*columns, &block)

Alias of group

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

Adds the appropriate CUBE syntax to GROUP BY.

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

Adds the appropriate ROLLUP syntax to GROUP BY.

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

Adds the appropriate GROUPING SETS syntax to GROUP BY.

[show source]
    # File lib/sequel/dataset/query.rb
412 def grouping_sets
413   raise Error, "GROUP BY GROUPING SETS not supported on #{db.database_type}" unless supports_grouping_sets?
414   clone(:group_options=>:"grouping sets")
415 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
421 def having(*cond, &block)
422   add_filter(:having, cond, &block)
423 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
442 def intersect(dataset, opts=OPTS)
443   raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
444   raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
445   compound_clone(:intersect, dataset, opts)
446 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
459 def invert
460   cached_dataset(:_invert_ds) do
461     having, where = @opts.values_at(:having, :where)
462     if having.nil? && where.nil?
463       where(false)
464     else
465       o = {}
466       o[:having] = SQL::BooleanExpression.invert(having) if having
467       o[:where] = SQL::BooleanExpression.invert(where) if where
468       clone(o)
469     end
470   end
471 end
join (*args, &block)

Alias of inner_join

[show source]
    # File lib/sequel/dataset/query.rb
474 def join(*args, &block)
475   inner_join(*args, &block)
476 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.

: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
537 def join_table(type, table, expr=nil, options=OPTS, &block)
538   if hoist_cte?(table)
539     s, ds = hoist_cte(table)
540     return s.join_table(type, ds, expr, options, &block)
541   end
542 
543   using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
544   if using_join && !supports_join_using?
545     h = {}
546     expr.each{|e| h[e] = e}
547     return join_table(type, table, h, options)
548   end
549 
550   table_alias = options[:table_alias]
551 
552   if table.is_a?(SQL::AliasedExpression)
553     table_expr = if table_alias
554       SQL::AliasedExpression.new(table.expression, table_alias, table.columns)
555     else
556       table
557     end
558     table = table_expr.expression
559     table_name = table_alias = table_expr.alias
560   elsif table.is_a?(Dataset)
561     if table_alias.nil?
562       table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
563       table_alias = dataset_alias(table_alias_num)
564     end
565     table_name = table_alias
566     table_expr = SQL::AliasedExpression.new(table, table_alias)
567   else
568     table, implicit_table_alias = split_alias(table)
569     table_alias ||= implicit_table_alias
570     table_name = table_alias || table
571     table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table
572   end
573 
574   join = if expr.nil? and !block
575     SQL::JoinClause.new(type, table_expr)
576   elsif using_join
577     raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
578     SQL::JoinUsingClause.new(expr, type, table_expr)
579   else
580     last_alias = options[:implicit_qualifier] || @opts[:last_joined_table] || first_source_alias
581     qualify_type = options[:qualify]
582     if Sequel.condition_specifier?(expr)
583       expr = expr.map do |k, v|
584         qualify_type = default_join_table_qualification if qualify_type.nil?
585         case qualify_type
586         when false
587           nil # Do no qualification
588         when :deep
589           k = Sequel::Qualifier.new(table_name).transform(k)
590           v = Sequel::Qualifier.new(last_alias).transform(v)
591         else
592           k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
593           v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
594         end
595         [k,v]
596       end
597       expr = SQL::BooleanExpression.from_value_pairs(expr)
598     end
599     if block
600       expr2 = yield(table_name, last_alias, @opts[:join] || EMPTY_ARRAY)
601       expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
602     end
603     SQL::JoinOnClause.new(expr, type, table_expr)
604   end
605 
606   opts = {:join => ((@opts[:join] || EMPTY_ARRAY) + [join]).freeze}
607   opts[:last_joined_table] = table_name unless options[:reset_implicit_qualifier] == false
608   opts[:num_dataset_sources] = table_alias_num if table_alias_num
609   clone(opts)
610 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
631 def lateral
632   cached_dataset(:_lateral_ds){clone(:lateral=>true)}
633 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
645 def limit(l, o = (no_offset = true; nil))
646   return from_self.limit(l, o) if @opts[:sql]
647 
648   if l.is_a?(Range)
649     no_offset = false
650     o = l.first
651     l = l.last - l.first + (l.exclude_end? ? 0 : 1)
652   end
653   l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
654   if l.is_a?(Integer)
655     raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
656   end
657 
658   ds = clone(:limit=>l)
659   ds = ds.offset(o) unless no_offset
660   ds
661 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
675 def lock_style(style)
676   clone(:lock => style)
677 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
684 def naked
685   cached_dataset(:_naked_ds){with_row_proc(nil)}
686 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
693 def nowait
694   cached_dataset(:_nowait_ds) do
695     raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait?
696     clone(:nowait=>true)
697   end
698 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 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
705 def offset(o)
706   o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
707   if o.is_a?(Integer)
708     raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
709   end
710   clone(:offset => o)
711 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
719 def or(*cond, &block)
720   if @opts[:where].nil?
721     self
722   else
723     add_filter(:where, cond, false, :OR, &block)
724   end
725 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
741 def order(*columns, &block)
742   virtual_row_columns(columns, block)
743   clone(:order => (columns.compact.empty?) ? nil : columns.freeze)
744 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
751 def order_append(*columns, &block)
752   columns = @opts[:order] + columns if @opts[:order]
753   order(*columns, &block)
754 end
order_by (*columns, &block)

Alias of order

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

Alias of order_append.

[show source]
    # File lib/sequel/dataset/query.rb
762 def order_more(*columns, &block)
763   order_append(*columns, &block)
764 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
771 def order_prepend(*columns, &block)
772   ds = order(*columns, &block)
773   @opts[:order] ? ds.order_append(*@opts[:order]) : ds
774 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
783 def qualify(table=(cache=true; first_source))
784   o = @opts
785   return self if o[:sql]
786 
787   pr = proc do
788     h = {}
789     (o.keys & QUALIFY_KEYS).each do |k|
790       h[k] = qualified_expression(o[k], table)
791     end
792     h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty?
793     clone(h)
794   end
795 
796   cache ? cached_dataset(:_qualify_ds, &pr) : pr.call
797 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
817 def returning(*values)
818   if values.empty?
819     cached_dataset(:_returning_ds) do
820       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
821       clone(:returning=>EMPTY_ARRAY)
822     end
823   else
824     raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
825     clone(:returning=>values.freeze)
826   end
827 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
836 def reverse(*order, &block)
837   if order.empty? && !block
838     cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))}
839   else
840     virtual_row_columns(order, block)
841     order(*invert_order(order.empty? ? @opts[:order] : order.freeze))
842   end
843 end
reverse_order (*order, &block)

Alias of reverse

[show source]
    # File lib/sequel/dataset/query.rb
846 def reverse_order(*order, &block)
847   reverse(*order, &block)
848 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
857 def select(*columns, &block)
858   virtual_row_columns(columns, block)
859   clone(:select => columns.freeze)
860 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
869 def select_all(*tables)
870   if tables.empty?
871     cached_dataset(:_select_all_ds){clone(:select => nil)}
872   else
873     select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze)
874   end
875 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
884 def select_append(*columns, &block)
885   cur_sel = @opts[:select]
886   if !cur_sel || cur_sel.empty?
887     unless supports_select_all_and_column?
888       return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_append(*columns, &block)
889     end
890     cur_sel = [WILDCARD]
891   end
892   select(*(cur_sel + columns), &block)
893 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
904 def select_group(*columns, &block)
905   virtual_row_columns(columns, block)
906   select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
907 end
select_more (*columns, &block)

Alias for select_append.

[show source]
    # File lib/sequel/dataset/query.rb
910 def select_more(*columns, &block)
911   select_append(*columns, &block)
912 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
923 def server(servr)
924   clone(:server=>servr)
925 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
930 def server?(server)
931   if db.sharded? && !opts[:server]
932     server(server)
933   else
934     self
935   end
936 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
939 def skip_limit_check
940   cached_dataset(:_skip_limit_check_ds) do
941     clone(:skip_limit_check=>true)
942   end
943 end
skip_locked ()

Skip locked rows when returning results from this dataset.

[show source]
    # File lib/sequel/dataset/query.rb
946 def skip_locked
947   cached_dataset(:_skip_locked_ds) do
948     raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked?
949     clone(:skip_locked=>true)
950   end
951 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
957 def unfiltered
958   cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)}
959 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
965 def ungrouped
966   cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)}
967 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
985 def union(dataset, opts=OPTS)
986   compound_clone(:union, dataset, opts)
987 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
992 def unlimited
993   cached_dataset(:_unlimited_ds){clone(:limit=>nil, :offset=>nil)}
994 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
 999 def unordered
1000   cached_dataset(:_unordered_ds){clone(:order=>nil)}
1001 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
1045 def where(*cond, &block)
1046   add_filter(:where, cond, &block)
1047 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
1055 def window(name, opts)
1056   clone(:window=>((@opts[:window]||EMPTY_ARRAY) + [[name, SQL::Window.new(opts)].freeze]).freeze)
1057 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

PostgreSQL Specific Options:

:materialized

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

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
1071 def with(name, dataset, opts=OPTS)
1072   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1073   if hoist_cte?(dataset)
1074     s, ds = hoist_cte(dataset)
1075     s.with(name, ds, opts)
1076   else
1077     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze)
1078   end
1079 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
1116 def with_extend(*mods, &block)
1117   c = _clone(:freeze=>false)
1118   c.extend(*mods) unless mods.empty?
1119   c.extend(DatasetModule.new(&block)) if block
1120   c.freeze
1121 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.

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
[show source]
     # File lib/sequel/dataset/query.rb
1097 def with_recursive(name, nonrecursive, recursive, opts=OPTS)
1098   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1099   if hoist_cte?(nonrecursive)
1100     s, ds = hoist_cte(nonrecursive)
1101     s.with_recursive(name, ds, recursive, opts)
1102   elsif hoist_cte?(recursive)
1103     s, ds = hoist_cte(recursive)
1104     s.with_recursive(name, nonrecursive, ds, opts)
1105   else
1106     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)
1107   end
1108 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
1138 def with_row_proc(callable)
1139   clone(:row_proc=>callable)
1140 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
1172 def with_sql(sql, *args)
1173   if sql.is_a?(Symbol)
1174     sql = public_send(sql, *args)
1175   else
1176     sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
1177   end
1178   clone(:sql=>sql)
1179 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
1184 def compound_clone(type, dataset, opts)
1185   if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds?
1186     s, ds = hoist_cte(dataset)
1187     return s.compound_clone(type, ds, opts)
1188   end
1189   ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze)
1190   opts[:from_self] == false ? ds : ds.from_self(opts)
1191 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
1194 def options_overlap(opts)
1195   !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty?
1196 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
1205 def simple_select_all?
1206   return false unless (f = @opts[:from]) && f.length == 1
1207   o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)}
1208   from = f.first
1209   from = from.expression if from.is_a?(SQL::AliasedExpression)
1210 
1211   if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)}
1212     case o.length
1213     when 1
1214       true
1215     when 2
1216       (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1217     else
1218       false
1219     end
1220   else
1221     false
1222   end
1223 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 => 1, :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
770 def as_hash(key_column, value_column = nil, opts = OPTS)
771   h = opts[:hash] || {}
772   meth = opts[:all] ? :all : :each
773   if value_column
774     return naked.as_hash(key_column, value_column, opts) if row_proc
775     if value_column.is_a?(Array)
776       if key_column.is_a?(Array)
777         public_send(meth){|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
778       else
779         public_send(meth){|r| h[r[key_column]] = r.values_at(*value_column)}
780       end
781     else
782       if key_column.is_a?(Array)
783         public_send(meth){|r| h[r.values_at(*key_column)] = r[value_column]}
784       else
785         public_send(meth){|r| h[r[key_column]] = r[value_column]}
786       end
787     end
788   elsif key_column.is_a?(Array)
789     public_send(meth){|r| h[key_column.map{|k| r[k]}] = r}
790   else
791     public_send(meth){|r| h[r[key_column]] = r}
792   end
793   h
794 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.

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

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

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

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

Options:

:commit_every

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

:return

When this is set to :primary_key, returns an array of autoincremented primary key values for the rows inserted. 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
340 def import(columns, values, opts=OPTS)
341   return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
342 
343   return if values.empty?
344   raise(Error, 'Using Sequel::Dataset#import with an empty column array is not allowed') if columns.empty?
345   ds = opts[:server] ? server(opts[:server]) : self
346   
347   if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
348     offset = 0
349     rows = []
350     while offset < values.length
351       rows << ds._import(columns, values[offset, slice_size], opts)
352       offset += slice_size
353     end
354     rows.flatten
355   else
356     ds._import(columns, values, opts)
357   end
358 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
396 def insert(*values, &block)
397   sql = insert_sql(*values)
398   if uses_returning?(:insert)
399     returning_fetch_rows(sql, &block)
400   else
401     execute_insert(sql)
402   end
403 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
415 def last(*args, &block)
416   raise(Error, 'No order specified') unless @opts[:order]
417   reverse.first(*args, &block)
418 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
434 def map(column=nil, &block)
435   if column
436     raise(Error, 'Must call Dataset#map with either an argument or a block, not both') if block
437     return naked.map(column) if row_proc
438     if column.is_a?(Array)
439       super(){|r| r.values_at(*column)}
440     else
441       super(){|r| r[column]}
442     end
443   else
444     super(&block)
445   end
446 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
455 def max(arg=(no_arg = true), &block)
456   arg = Sequel.virtual_row(&block) if no_arg
457   _aggregate(:max, arg)
458 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
467 def min(arg=(no_arg = true), &block)
468   arg = Sequel.virtual_row(&block) if no_arg
469   _aggregate(:min, arg)
470 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
484 def multi_insert(hashes, opts=OPTS)
485   return if hashes.empty?
486   columns = hashes.first.keys
487   import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
488 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
545 def paged_each(opts=OPTS)
546   unless @opts[:order]
547     raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
548   end
549   unless block_given?
550     return enum_for(:paged_each, opts)
551   end
552 
553   total_limit = @opts[:limit]
554   offset = @opts[:offset]
555   if server = @opts[:server]
556     opts = Hash[opts]
557     opts[:server] = server
558   end
559 
560   rows_per_fetch = opts[:rows_per_fetch] || 1000
561   strategy = if offset || total_limit
562     :offset
563   else
564     opts[:strategy] || :offset
565   end
566 
567   db.transaction(opts) do
568     case strategy
569     when :filter
570       filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
571       base_ds = ds = limit(rows_per_fetch)
572       while ds
573         last_row = nil
574         ds.each do |row|
575           last_row = row
576           yield row
577         end
578         ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
579       end
580     else
581       offset ||= 0
582       num_rows_yielded = rows_per_fetch
583       total_rows = 0
584 
585       while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
586         if total_limit && total_rows + rows_per_fetch > total_limit
587           rows_per_fetch = total_limit - total_rows
588         end
589 
590         num_rows_yielded = 0
591         limit(rows_per_fetch, offset).each do |row|
592           num_rows_yielded += 1
593           total_rows += 1 if total_limit
594           yield row
595         end
596 
597         offset += rows_per_fetch
598       end
599     end
600   end
601 
602   self
603 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 * 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
621 def select_hash(key_column, value_column, opts = OPTS)
622   _select_hash(:as_hash, key_column, value_column, opts)
623 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 * 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
640 def select_hash_groups(key_column, value_column, opts = OPTS)
641   _select_hash(:to_hash_groups, key_column, value_column, opts)
642 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
663 def select_map(column=nil, &block)
664   _select_map(column, false, &block)
665 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
682 def select_order_map(column=nil, &block)
683   _select_map(column, true, &block)
684 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
692 def single_record
693   _single_record_ds.single_record!
694 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
704 def single_record!
705   with_sql_first(select_sql)
706 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
714 def single_value
715   single_value_ds.each do |r|
716     r.each{|_, v| return v}
717   end
718   nil
719 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
729 def single_value!
730   with_sql_single_value(select_sql)
731 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
740 def sum(arg=(no_arg = true), &block)
741   arg = Sequel.virtual_row(&block) if no_arg
742   _aggregate(:sum, arg)
743 end
to_hash (*a)

Alias of as_hash for backwards compatibility.

[show source]
    # File lib/sequel/dataset/actions.rb
797 def to_hash(*a)
798   as_hash(*a)
799 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
825 def to_hash_groups(key_column, value_column = nil, opts = OPTS)
826   h = opts[:hash] || {}
827   meth = opts[:all] ? :all : :each
828   if value_column
829     return naked.to_hash_groups(key_column, value_column, opts) if row_proc
830     if value_column.is_a?(Array)
831       if key_column.is_a?(Array)
832         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
833       else
834         public_send(meth){|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
835       end
836     else
837       if key_column.is_a?(Array)
838         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
839       else
840         public_send(meth){|r| (h[r[key_column]] ||= []) << r[value_column]}
841       end
842     end
843   elsif key_column.is_a?(Array)
844     public_send(meth){|r| (h[key_column.map{|k| r[k]}] ||= []) << r}
845   else
846     public_send(meth){|r| (h[r[key_column]] ||= []) << r}
847   end
848   h
849 end
truncate ()

Truncates the dataset. Returns nil.

DB[:table].truncate # TRUNCATE table
# => nil
[show source]
    # File lib/sequel/dataset/actions.rb
855 def truncate
856   execute_ddl(truncate_sql)
857 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
868 def update(values=OPTS, &block)
869   sql = update_sql(values)
870   if uses_returning?(:update)
871     returning_fetch_rows(sql, &block)
872   else
873     execute_dui(sql)
874   end
875 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
883 def where_all(cond, &block)
884   if loader = _where_loader([cond], nil)
885     loader.all(filter_expr(cond), &block)
886   else
887     where(cond).all(&block)
888   end
889 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
897 def where_each(cond, &block)
898   if loader = _where_loader([cond], nil)
899     loader.each(filter_expr(cond), &block)
900   else
901     where(cond).each(&block)
902   end
903 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
912 def where_single_value(cond)
913   if loader = cached_where_placeholder_literalizer([cond], nil, :_where_single_value_loader) do |pl|
914       single_value_ds.where(pl.arg)
915     end
916 
917     loader.get(filter_expr(cond))
918   else
919     where(cond).single_value
920   end
921 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
925 def with_sql_all(sql, &block)
926   _all(block){|a| with_sql_each(sql){|r| a << r}}
927 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
932 def with_sql_delete(sql)
933   execute_dui(sql)
934 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
938 def with_sql_each(sql)
939   if rp = row_proc
940     _with_sql_dataset.fetch_rows(sql){|r| yield rp.call(r)}
941   else
942     _with_sql_dataset.fetch_rows(sql){|r| yield r}
943   end
944   self
945 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
949 def with_sql_first(sql)
950   with_sql_each(sql){|r| return r}
951   nil
952 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
965 def with_sql_insert(sql)
966   execute_insert(sql)
967 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
957 def with_sql_single_value(sql)
958   if r = with_sql_first(sql)
959     r.each{|_, v| return v}
960   end
961 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.

[show source]
    # File lib/sequel/dataset/actions.rb
974 def _import(columns, values, opts)
975   trans_opts = Hash[opts]
976   trans_opts[:server] = @opts[:server]
977   if opts[:return] == :primary_key
978     @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
979   else
980     stmts = multi_insert_sql(columns, values)
981     @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
982   end
983 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
986 def _select_map_multiple(ret_cols)
987   map{|r| r.values_at(*ret_cols)}
988 end
_select_map_single ()

Returns an array of the first value in each row.

[show source]
    # File lib/sequel/dataset/actions.rb
991 def _select_map_single
992   k = nil
993   map{|r| r[k||=r.keys.first]}
994 end
single_value_ds ()

A dataset for returning single values from the current dataset.

[show source]
    # File lib/sequel/dataset/actions.rb
997 def single_value_ds
998   clone(:limit=>1).ungraphed.naked
999 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_modification_allowed!
26 
27   columns = []
28 
29   case values.size
30   when 0
31     return insert_sql(OPTS)
32   when 1
33     case vals = values[0]
34     when Hash
35       values = []
36       vals.each do |k,v| 
37         columns << k
38         values << v
39       end
40     when Dataset, Array, LiteralString
41       values = vals
42     end
43   when 2
44     if (v0 = values[0]).is_a?(Array) && ((v1 = values[1]).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
45       columns, values = v0, v1
46       raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
47     end
48   end
49 
50   if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
51     columns, values = insert_empty_columns_values
52   elsif values.is_a?(Dataset) && hoist_cte?(values) && supports_cte?(:insert)
53     ds, values = hoist_cte(values)
54     return ds.clone(:columns=>columns, :values=>values).send(:_insert_sql)
55   end
56   clone(:columns=>columns, :values=>values).send(:_insert_sql)
57 end
literal_append (sql, v)

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

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

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

[show source]
    # File lib/sequel/dataset/sql.rb
146 def sql
147   select_sql
148 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
153 def truncate_sql
154   if opts[:sql]
155     static_sql(opts[:sql])
156   else
157     check_truncation_allowed!
158     check_not_limited!(:truncate)
159     raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
160     t = String.new
161     source_list_append(t, opts[:from])
162     _truncate_sql(t)
163   end
164 end
update_sql (values = OPTS)

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

4 - Methods that describe what the dataset supports

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_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
57 def supports_derived_column_lists?
58   true
59 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
62 def supports_distinct_on?
63   false
64 end
supports_group_cube? ()

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

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

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

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

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

[show source]
   # File lib/sequel/dataset/features.rb
77 def supports_grouping_sets?
78   false
79 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
83 def supports_insert_select?
84   supports_returning?(:insert)
85 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
88 def supports_intersect_except?
89   true
90 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
93 def supports_intersect_except_all?
94   true
95 end
supports_is_true? ()

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

[show source]
    # File lib/sequel/dataset/features.rb
 98 def supports_is_true?
 99   true
100 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
104 def supports_join_using?
105   true
106 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
109 def supports_lateral_subqueries?
110   false
111 end
supports_limits_in_correlated_subqueries? ()

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

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

Whether modifying joined datasets is supported, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
124 def supports_modifying_joins?
125   false
126 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
130 def supports_multiple_column_in?
131   true
132 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
119 def supports_nowait?
120   false
121 end
supports_offsets_in_correlated_subqueries? ()

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

[show source]
    # File lib/sequel/dataset/features.rb
135 def supports_offsets_in_correlated_subqueries?
136   true
137 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
141 def supports_ordered_distinct_on?
142   supports_distinct_on?
143 end
supports_regexp? ()

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

[show source]
    # File lib/sequel/dataset/features.rb
146 def supports_regexp?
147   false
148 end
supports_replace? ()

Whether the dataset supports REPLACE syntax, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
151 def supports_replace?
152   false
153 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
157 def supports_returning?(type)
158   false
159 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
167 def supports_select_all_and_column?
168   true
169 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
162 def supports_skip_locked?
163   false
164 end
supports_timestamp_timezones? ()

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

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

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

[show source]
    # File lib/sequel/dataset/features.rb
177 def supports_timestamp_usecs?
178   true
179 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
206 def supports_where_true?
207   true
208 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
183 def supports_window_clause?
184   false
185 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
195 def supports_window_function_frame_option?(option)
196   case option
197   when :rows, :range, :offset
198     true
199   else
200     false
201   end
202 end
supports_window_functions? ()

Whether the dataset supports window functions, false by default.

[show source]
    # File lib/sequel/dataset/features.rb
188 def supports_window_functions?
189   false
190 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
330 def bind(bind_vars=OPTS)
331   bind_vars = if bv = @opts[:bind_vars]
332     bv.merge(bind_vars).freeze
333   else
334     if bind_vars.frozen?
335       bind_vars
336     else
337       Hash[bind_vars]
338     end
339   end
340 
341   clone(:bind_vars=>bind_vars)
342 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
351 def call(type, bind_variables=OPTS, *values, &block)
352   to_prepared_statement(type, values, :extend=>bound_variable_modules).call(bind_variables, &block)
353 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
371 def prepare(type, name, *values)
372   ps = to_prepared_statement(type, values, :name=>name, :extend=>prepared_statement_modules, :no_delayed_evaluations=>true)
373 
374   ps = if ps.send(:emulate_prepared_statements?)
375     ps = ps.with_extend(EmulatePreparedStatementMethods)
376     ps.send(:emulated_prepared_statement, type, name, values)
377   else
378     sql = ps.prepared_sql
379     ps.prepared_args.freeze
380     ps.clone(:prepared_sql=>sql, :sql=>sql)
381   end
382 
383   db.set_prepared_statement(name, ps)
384   ps
385 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
391 def to_prepared_statement(type, values=nil, opts=OPTS)
392   mods = opts[:extend] || []
393   mods += [PreparedStatementMethods]
394 
395   bind.
396     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]).
397     with_extend(*mods)
398 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
195 def self.clause_methods(type, clauses)
196   clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
197 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
209 def self.def_sql_method(mod, type, clauses)
210   priv = type == :update || type == :insert
211   cacheable = type == :select || type == :delete
212 
213   lines = []
214   lines << 'private' if priv
215   lines << "def #{'_' if priv}#{type}_sql"
216   lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
217   lines << "if sql = cache_get(:_#{type}_sql); return sql end" if cacheable
218   lines << 'check_modification_allowed!' << 'check_not_limited!(:delete)' if type == :delete
219   lines << 'sql = @opts[:append_sql] || sql_string_origin'
220 
221   if clauses.all?{|c| c.is_a?(Array)}
222     clauses.each do |i, cs|
223       lines << i
224       lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 
225     end 
226     lines << 'end'
227   else
228     lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
229   end
230 
231   lines << "cache_set(:_#{type}_sql, sql) if cache_sql?" if cacheable
232   lines << 'sql'
233   lines << 'end'
234 
235   mod.class_eval lines.join("\n"), __FILE__, __LINE__
236 end

Public Instance methods

aliased_expression_sql_append (sql, ae)

Append literalization of aliased expression to SQL string.

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

Append literalization of array to SQL string.

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

Append literalization of boolean constant to SQL string.

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

Append literalization of case expression to SQL string.

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

Append literalization of cast expression to SQL string.

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

Append literalization of column all selection to SQL string.

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

Append literalization of complex expression to SQL string.

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

Append literalization of constant to SQL string.

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

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

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

Append literalization of function call to SQL string.

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

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

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

Append literalization of JOIN ON clause to SQL string.

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

Append literalization of JOIN USING clause to SQL string.

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

Append literalization of negative boolean constant to SQL string.

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

Append literalization of ordered expression to SQL string.

[show source]
    # File lib/sequel/dataset/sql.rb
561 def ordered_expression_sql_append(sql, oe)
562   if emulate = requires_emulating_nulls_first?
563     case oe.nulls
564     when :first
565       null_order = 0
566     when :last
567       null_order = 2
568     end
569 
570     if null_order
571       literal_append(sql, Sequel.case({{oe.expression=>nil}=>null_order}, 1))
572       sql << ", "
573     end
574   end
575 
576   literal_append(sql, oe.expression)
577   sql << (oe.descending ? ' DESC' : ' ASC')
578 
579   unless emulate
580     case oe.nulls
581     when :first
582       sql << " NULLS FIRST"
583     when :last
584       sql << " NULLS LAST"
585     end
586   end
587 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
590 def placeholder_literal_string_sql_append(sql, pls)
591   args = pls.args
592   str = pls.str
593   sql << '(' if pls.parens
594   if args.is_a?(Hash)
595     if args.empty?
596       sql << str
597     else
598       re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
599       while true
600         previous, q, str = str.partition(re)
601         sql << previous
602         literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
603         break if str.empty?
604       end
605     end
606   elsif str.is_a?(Array)
607     len = args.length
608     str.each_with_index do |s, i|
609       sql << s
610       literal_append(sql, args[i]) unless i == len
611     end
612     unless str.length == args.length || str.length == args.length + 1
613       raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
614     end
615   else
616     i = -1
617     match_len = args.length - 1
618     while true
619       previous, q, str = str.partition('?')
620       sql << previous
621       literal_append(sql, args.at(i+=1)) unless q.empty?
622       if str.empty?
623         unless i == match_len
624           raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder string"
625         end
626         break
627       end
628     end
629   end
630   sql << ')' if pls.parens
631 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
636 def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
637   identifier_append(sql, table)
638   sql << '.'
639   identifier_append(sql, column)
640 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
646 def quote_identifier_append(sql, name)
647   if name.is_a?(LiteralString)
648     sql << name
649   else
650     name = name.value if name.is_a?(SQL::Identifier)
651     name = input_identifier(name)
652     if quote_identifiers?
653       quoted_identifier_append(sql, name)
654     else
655       sql << name
656     end
657   end
658 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
661 def quote_schema_table_append(sql, table)
662   schema, table = schema_and_table(table)
663   if schema
664     quote_identifier_append(sql, schema)
665     sql << '.'
666   end
667   quote_identifier_append(sql, table)
668 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
674 def quoted_identifier_append(sql, name)
675   sql << '"' << name.to_s.gsub('"', '""') << '"'
676 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
685 def schema_and_table(table_name, sch=nil)
686   sch = sch.to_s if sch
687   case table_name
688   when Symbol
689     s, t, _ = split_symbol(table_name)
690     [s||sch, t]
691   when SQL::QualifiedIdentifier
692     [table_name.table.to_s, table_name.column.to_s]
693   when SQL::Identifier
694     [sch, table_name.value.to_s]
695   when String
696     [sch, table_name]
697   else
698     raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
699   end
700 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
708 def split_qualifiers(table_name, *args)
709   case table_name
710   when SQL::QualifiedIdentifier
711     split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
712   else
713     sch, table = schema_and_table(table_name, *args)
714     sch ? [sch, table] : [table]
715   end
716 end
subscript_sql_append (sql, s)

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

[show source]
    # File lib/sequel/dataset/sql.rb
719 def subscript_sql_append(sql, s)
720   case s.expression
721   when Symbol, SQL::Subscript, SQL::Identifier, SQL::QualifiedIdentifier
722     # nothing
723   else
724     wrap_expression = true
725     sql << '('
726   end
727   literal_append(sql, s.expression)
728   if wrap_expression
729     sql << ')['
730   else
731     sql << '['
732   end
733   sub = s.sub
734   if sub.length == 1 && (range = sub.first).is_a?(Range)
735     literal_append(sql, range.begin)
736     sql << ':'
737     e = range.end
738     e -= 1 if range.exclude_end? && e.is_a?(Integer)
739     literal_append(sql, e)
740   else
741     expression_list_append(sql, s.sub)
742   end
743   sql << ']'
744 end
window_sql_append (sql, opts)

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

[show source]
    # File lib/sequel/dataset/sql.rb
747 def window_sql_append(sql, opts)
748   raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
749   space = false
750   space_s = ' '
751 
752   sql << '('
753 
754   if window = opts[:window]
755     literal_append(sql, window)
756     space = true
757   end
758 
759   if part = opts[:partition]
760     sql << space_s if space
761     sql << "PARTITION BY "
762     expression_list_append(sql, Array(part))
763     space = true
764   end
765 
766   if order = opts[:order]
767     sql << space_s if space
768     sql << "ORDER BY "
769     expression_list_append(sql, Array(order))
770     space = true
771   end
772 
773   if frame = opts[:frame]
774     sql << space_s if space
775 
776     if frame.is_a?(String)
777       sql << frame
778     else
779       case frame
780       when :all
781         frame_type = :rows
782         frame_start = :preceding
783         frame_end = :following
784       when :rows, :range, :groups
785         frame_type = frame
786         frame_start = :preceding
787         frame_end = :current
788       when Hash
789         frame_type = frame[:type]
790         unless frame_type == :rows || frame_type == :range || frame_type == :groups
791           raise Error, "invalid window :frame :type option: #{frame_type.inspect}"
792         end
793         unless frame_start = frame[:start]
794           raise Error, "invalid window :frame :start option: #{frame_start.inspect}"
795         end
796         frame_end = frame[:end]
797         frame_exclude = frame[:exclude]
798       else
799         raise Error, "invalid window :frame option: #{frame.inspect}"
800       end
801 
802       sql << frame_type.to_s.upcase << " "
803       sql << 'BETWEEN ' if frame_end
804       window_frame_boundary_sql_append(sql, frame_start, :preceding)
805       if frame_end
806         sql << " AND "
807         window_frame_boundary_sql_append(sql, frame_end, :following)
808       end
809 
810       if frame_exclude
811         sql << " EXCLUDE "
812 
813         case frame_exclude
814         when :current
815           sql << "CURRENT ROW"
816         when :group
817           sql << "GROUP"
818         when :ties
819           sql << "TIES"
820         when :no_others
821           sql << "NO OTHERS"
822         else
823           raise Error, "invalid window :frame :exclude option: #{frame_exclude.inspect}"
824         end
825       end
826     end
827   end
828 
829   sql << ')'
830 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
836 def compound_from_self
837   (@opts[:sql] || @opts[:limit] || @opts[:order] || @opts[:offset]) ? from_self : self
838 end