A dataset represents an SQL query, or more generally, an abstract set of rows in the database. Datasets can be used to create, retrieve, 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].filter(:author => 'david') # no records are retrieved my_posts.all # records are retrieved my_posts.all # records are retrieved again
Most dataset methods return modified copies of the dataset (functional style), so you can reuse different datasets to access data:
posts = DB[:posts]
davids_posts = posts.filter(:author => 'david')
old_posts = posts.filter('stamp < ?', Date.today - 7)
davids_old_posts = davids_posts.filter('stamp < ?', Date.today - 7)
Datasets are Enumerable objects, so they can be manipulated using any of the Enumerable methods, such as map, inject, etc.
For more information, see the "Dataset Basics" guide.
| columns | -> | columns_without_introspection |
Enable column introspection for every dataset.
# File lib/sequel/extensions/columns_introspection.rb, line 56
56: def self.introspect_all_columns
57: include ColumnsIntrospection
58: remove_method(:columns) if instance_methods(false).map{|x| x.to_s}.include?('columns')
59: end
Yields a paginated dataset for each page and returns the receiver. Does a count to find the total number of records for this dataset.
# File lib/sequel/extensions/pagination.rb, line 20
20: def each_page(page_size)
21: raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit]
22: record_count = count
23: total_pages = (record_count / page_size.to_f).ceil
24: (1..total_pages).each{|page_no| yield paginate(page_no, page_size, record_count)}
25: self
26: end
Returns a paginated dataset. The returned dataset is limited to the page size at the correct offset, and extended with the Pagination module. If a record count is not provided, does a count of total number of records for this dataset.
# File lib/sequel/extensions/pagination.rb, line 11
11: def paginate(page_no, page_size, record_count=nil)
12: raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit]
13: paginated = limit(page_size, (page_no - 1) * page_size)
14: paginated.extend(Pagination)
15: paginated.set_pagination_info(page_no, page_size, record_count || count)
16: end
Pretty prints the records in the dataset as plain-text table.
# File lib/sequel/extensions/pretty_table.rb, line 8
8: def print(*cols)
9: Sequel::PrettyTable.print(naked.all, cols.empty? ? columns : cols)
10: end
Translates a query block into a dataset. Query blocks can be useful when expressing complex SELECT statements, e.g.:
dataset = DB[:items].query do
select :x, :y, :z
filter{|o| (o.x > 1) & (o.y > 2)}
order :z.desc
end
Which is the same as:
dataset = DB[:items].select(:x, :y, :z).filter{|o| (o.x > 1) & (o.y > 2)}.order(:z.desc)
Note that inside a call to query, you cannot call each, insert, update, or delete (or any method that calls those), or Sequel will raise an error.
# File lib/sequel/extensions/query.rb, line 30
30: def query(&block)
31: copy = clone({})
32: copy.extend(QueryBlockCopy)
33: copy.instance_eval(&block)
34: clone(copy.opts)
35: end
Whether this dataset quotes identifiers.
# File lib/sequel/dataset/features.rb, line 10
10: def quote_identifiers?
11: if defined?(@quote_identifiers)
12: @quote_identifiers
13: elsif db.respond_to?(:quote_identifiers?)
14: @quote_identifiers = db.quote_identifiers?
15: else
16: @quote_identifiers = false
17: end
18: end
Whether you must use a column alias list for recursive CTEs (false by default).
# File lib/sequel/dataset/features.rb, line 29
29: def recursive_cte_requires_column_aliases?
30: false
31: end
Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer)
# File lib/sequel/dataset/features.rb, line 41
41: def requires_placeholder_type_specifiers?
42: false
43: end
Whether the dataset supports common table expressions (the WITH clause). If given, type can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.
# File lib/sequel/dataset/features.rb, line 48
48: def supports_cte?(type=:select)
49: send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_with_sql""#{type}_with_sql")
50: end
Whether the dataset supports common table expressions (the WITH clause) in subqueries. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.
# File lib/sequel/dataset/features.rb, line 55
55: def supports_cte_in_subqueries?
56: false
57: end
Whether the dataset supports the IS TRUE syntax.
# File lib/sequel/dataset/features.rb, line 91
91: def supports_is_true?
92: true
93: end
Whether the dataset supports the JOIN table USING (column1, …) syntax.
# File lib/sequel/dataset/features.rb, line 96
96: def supports_join_using?
97: true
98: end
Whether modifying joined datasets is supported.
# File lib/sequel/dataset/features.rb, line 101
101: def supports_modifying_joins?
102: false
103: end
Whether the RETURNING clause is supported for the given type of query. type can be :insert, :update, or :delete.
# File lib/sequel/dataset/features.rb, line 119
119: def supports_returning?(type)
120: send("#{type}_clause_methods""#{type}_clause_methods").include?("#{type}_returning_sql""#{type}_returning_sql")
121: end
Whether the database supports SELECT *, column FROM table
# File lib/sequel/dataset/features.rb, line 124
124: def supports_select_all_and_column?
125: true
126: end
Whether the dataset supports timezones in literal timestamps
# File lib/sequel/dataset/features.rb, line 129
129: def supports_timestamp_timezones?
130: false
131: end
Whether the dataset supports fractional seconds in literal timestamps
# File lib/sequel/dataset/features.rb, line 134
134: def supports_timestamp_usecs?
135: true
136: end
Returns a DELETE SQL query string. See delete.
dataset.filter{|o| o.price >= 100}.delete_sql
# => "DELETE FROM items WHERE (price >= 100)"
# File lib/sequel/dataset/sql.rb, line 12
12: def delete_sql
13: return static_sql(opts[:sql]) if opts[:sql]
14: check_modification_allowed!
15: clause_sql(:delete)
16: end
Returns an EXISTS clause for the dataset as a LiteralString.
DB.select(1).where(DB[:items].exists) # SELECT 1 WHERE (EXISTS (SELECT * FROM items))
# File lib/sequel/dataset/sql.rb, line 22
22: def exists
23: SQL::PlaceholderLiteralString.new("EXISTS ?", [self], true)
24: end
Returns an INSERT SQL query string. See insert.
DB[:items].insert_sql(:a=>1) # => "INSERT INTO items (a) VALUES (1)"
# File lib/sequel/dataset/sql.rb, line 30
30: def insert_sql(*values)
31: return static_sql(@opts[:sql]) if @opts[:sql]
32:
33: check_modification_allowed!
34:
35: columns = []
36:
37: case values.size
38: when 0
39: return insert_sql({})
40: when 1
41: case vals = values.at(0)
42: when Hash
43: vals = @opts[:defaults].merge(vals) if @opts[:defaults]
44: vals = vals.merge(@opts[:overrides]) if @opts[:overrides]
45: values = []
46: vals.each do |k,v|
47: columns << k
48: values << v
49: end
50: when Dataset, Array, LiteralString
51: values = vals
52: else
53: if vals.respond_to?(:values) && (v = vals.values).is_a?(Hash)
54: return insert_sql(v)
55: end
56: end
57: when 2
58: if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
59: columns, values = v0, v1
60: raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
61: end
62: end
63:
64: if values.is_a?(Array) && values.empty? && !insert_supports_empty_values?
65: columns = [columns().last]
66: values = ['DEFAULT'.lit]
67: end
68: clone(:columns=>columns, :values=>values)._insert_sql
69: end
Returns a literal representation of a value to be used as part of an SQL expression.
DB[:items].literal("abc'def\\") #=> "'abc''def\\\\'"
DB[:items].literal(:items__id) #=> "items.id"
DB[:items].literal([1, 2, 3]) => "(1, 2, 3)"
DB[:items].literal(DB[:items]) => "(SELECT * FROM items)"
DB[:items].literal(:x + 1 > :y) => "((x + 1) > y)"
If an unsupported object is given, an Error is raised.
# File lib/sequel/dataset/sql.rb, line 81
81: def literal_append(sql, v)
82: case v
83: when Symbol
84: literal_symbol_append(sql, v)
85: when String
86: case v
87: when LiteralString
88: sql << v
89: when SQL::Blob
90: literal_blob_append(sql, v)
91: else
92: literal_string_append(sql, v)
93: end
94: when Integer
95: sql << literal_integer(v)
96: when Hash
97: literal_hash_append(sql, v)
98: when SQL::Expression
99: literal_expression_append(sql, v)
100: when Float
101: sql << literal_float(v)
102: when BigDecimal
103: sql << literal_big_decimal(v)
104: when NilClass
105: sql << literal_nil
106: when TrueClass
107: sql << literal_true
108: when FalseClass
109: sql << literal_false
110: when Array
111: literal_array_append(sql, v)
112: when Time
113: sql << (v.is_a?(SQLTime) ? literal_sqltime(v) : literal_time(v))
114: when DateTime
115: sql << literal_datetime(v)
116: when Date
117: sql << literal_date(v)
118: when Dataset
119: literal_dataset_append(sql, v)
120: else
121: literal_other_append(sql, v)
122: end
123: end
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.
This method should be overridden by descendants if the support inserting multiple records in a single SQL statement.
# File lib/sequel/dataset/sql.rb, line 131
131: def multi_insert_sql(columns, values)
132: values.map{|r| insert_sql(columns, r)}
133: end
Same as select_sql, not aliased directly to make subclassing simpler.
# File lib/sequel/dataset/sql.rb, line 144
144: def sql
145: select_sql
146: end
Returns a TRUNCATE SQL query string. See truncate
DB[:items].truncate_sql # => 'TRUNCATE items'
# File lib/sequel/dataset/sql.rb, line 151
151: def truncate_sql
152: if opts[:sql]
153: static_sql(opts[:sql])
154: else
155: check_modification_allowed!
156: raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where]
157: _truncate_sql(source_list(opts[:from]))
158: end
159: end
Formats an UPDATE statement using the given values. See update.
DB[:items].update_sql(:price => 100, :category => 'software') # => "UPDATE items SET price = 100, category = 'software'
Raises an Error if the dataset is grouped or includes more than one table.
# File lib/sequel/dataset/sql.rb, line 168
168: def update_sql(values = {})
169: return static_sql(opts[:sql]) if opts[:sql]
170: check_modification_allowed!
171: clone(:values=>values)._update_sql
172: end
These methods, while public, are not designed to be used directly by the end user.
| ALL | = | ' ALL'.freeze |
| AND_SEPARATOR | = | " AND ".freeze |
| APOS | = | "'".freeze |
| APOS_RE | = | /'/.freeze |
| ARRAY_EMPTY | = | '(NULL)'.freeze |
| AS | = | ' AS '.freeze |
| ASC | = | ' ASC'.freeze |
| BACKSLASH_RE | = | /\\/.freeze |
| BOOL_FALSE | = | "'f'".freeze |
| BOOL_TRUE | = | "'t'".freeze |
| BRACKET_CLOSE | = | ']'.freeze |
| BRACKET_OPEN | = | '['.freeze |
| CASE_ELSE | = | " ELSE ".freeze |
| CASE_END | = | " END)".freeze |
| CASE_OPEN | = | '(CASE'.freeze |
| CASE_THEN | = | " THEN ".freeze |
| CASE_WHEN | = | " WHEN ".freeze |
| CAST_OPEN | = | 'CAST('.freeze |
| COLUMN_ALL | = | '.*'.freeze |
| COLUMN_REF_RE1 | = | /\A((?:(?!__).)+)__((?:(?!___).)+)___(.+)\z/.freeze |
| COLUMN_REF_RE2 | = | /\A((?:(?!___).)+)___(.+)\z/.freeze |
| COLUMN_REF_RE3 | = | /\A((?:(?!__).)+)__(.+)\z/.freeze |
| COMMA | = | ', '.freeze |
| COMMA_SEPARATOR | = | COMMA |
| CONDITION_FALSE | = | '(1 = 0)'.freeze |
| CONDITION_TRUE | = | '(1 = 1)'.freeze |
| COUNT_FROM_SELF_OPTS | = | [:distinct, :group, :sql, :limit, :compounds] |
| COUNT_OF_ALL_AS_COUNT | = | SQL::Function.new(:count, LiteralString.new('*'.freeze)).as(:count) |
| DATASET_ALIAS_BASE_NAME | = | 't'.freeze |
| DEFAULT_VALUES | = | " DEFAULT VALUES".freeze |
| DELETE | = | 'DELETE'.freeze |
| DELETE_CLAUSE_METHODS | = | clause_methods(:delete, %w'delete from where') |
| DESC | = | ' DESC'.freeze |
| DISTINCT | = | " DISTINCT".freeze |
| DOT | = | '.'.freeze |
| DOUBLE_APOS | = | "''".freeze |
| DOUBLE_QUOTE | = | '""'.freeze |
| EQUAL | = | ' = '.freeze |
| EXTRACT | = | 'extract('.freeze |
| FOR_UPDATE | = | ' FOR UPDATE'.freeze |
| FORMAT_DATE | = | "'%Y-%m-%d'".freeze |
| FORMAT_DATE_STANDARD | = | "DATE '%Y-%m-%d'".freeze |
| FORMAT_OFFSET | = | "%+03i%02i".freeze |
| FORMAT_TIMESTAMP_RE | = | /%[Nz]/.freeze |
| FORMAT_TIMESTAMP_USEC | = | ".%06d".freeze |
| FORMAT_USEC | = | '%N'.freeze |
| FRAME_ALL | = | "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING".freeze |
| FRAME_ROWS | = | "ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW".freeze |
| FROM | = | ' FROM '.freeze |
| FUNCTION_EMPTY | = | '()'.freeze |
| GROUP_BY | = | " GROUP BY ".freeze |
| HAVING | = | " HAVING ".freeze |
| INSERT | = | "INSERT".freeze |
| INSERT_CLAUSE_METHODS | = | clause_methods(:insert, %w'insert into columns values') |
| INTO | = | " INTO ".freeze |
| IS_LITERALS | = | {nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze |
| IS_OPERATORS | = | ::Sequel::SQL::ComplexExpression::IS_OPERATORS |
| LIMIT | = | " LIMIT ".freeze |
| N_ARITY_OPERATORS | = | ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS |
| NOT_SPACE | = | 'NOT '.freeze |
| NULL | = | "NULL".freeze |
| NULLS_FIRST | = | " NULLS FIRST".freeze |
| NULLS_LAST | = | " NULLS LAST".freeze |
| OFFSET | = | " OFFSET ".freeze |
| ON | = | ' ON '.freeze |
| ON_PAREN | = | " ON (".freeze |
| ORDER_BY | = | " ORDER BY ".freeze |
| ORDER_BY_NS | = | "ORDER BY ".freeze |
| OVER | = | ' OVER '.freeze |
| PAREN_CLOSE | = | ')'.freeze |
| PAREN_OPEN | = | '('.freeze |
| PAREN_SPACE_OPEN | = | ' ('.freeze |
| PARTITION_BY | = | "PARTITION BY ".freeze |
| QUAD_BACKSLASH | = | "\\\\\\\\".freeze |
| QUALIFY_KEYS | = | [:select, :where, :having, :order, :group] |
| QUESTION_MARK | = | '?'.freeze |
| QUESTION_MARK_RE | = | /\?/.freeze |
| QUOTE | = | '"'.freeze |
| QUOTE_RE | = | /"/.freeze |
| RETURNING | = | " RETURNING ".freeze |
| SELECT | = | 'SELECT'.freeze |
| SELECT_CLAUSE_METHODS | = | clause_methods(:select, %w'with select distinct columns from join where group having compounds order limit lock') |
| SET | = | ' SET '.freeze |
| SPACE | = | ' '.freeze |
| SQL_WITH | = | "WITH ".freeze |
| TILDE | = | '~'.freeze |
| TIMESTAMP_FORMAT | = | "'%Y-%m-%d %H:%M:%S%N%z'".freeze |
| STANDARD_TIMESTAMP_FORMAT | = | "TIMESTAMP #{TIMESTAMP_FORMAT}".freeze |
| TWO_ARITY_OPERATORS | = | ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS |
| UNDERSCORE | = | '_'.freeze |
| UPDATE | = | 'UPDATE'.freeze |
| UPDATE_CLAUSE_METHODS | = | clause_methods(:update, %w'update table set where') |
| USING | = | ' USING ('.freeze |
| VALUES | = | " VALUES ".freeze |
| WHERE | = | " WHERE ".freeze |
| WILDCARD | = | LiteralString.new('*').freeze |
| PUBLIC_APPEND_METHODS | = | (<<-END).split.map{|x| x.to_sym} literal aliased_expression_sql array_sql boolean_constant_sql case_expression_sql cast_sql column_all_sql complex_expression_sql constant_sql function_sql join_clause_sql join_on_clause_sql join_using_clause_sql negative_boolean_constant_sql ordered_expression_sql placeholder_literal_string_sql qualified_identifier_sql quote_identifier quote_schema_table quoted_identifier subscript_sql window_sql window_function_sql END ).split.map{|x| x.to_sym} |
| PRIVATE_APPEND_METHODS | = | (<<-END).split.map{|x| x.to_sym} argument_list as_sql column_list compound_dataset_sql expression_list literal_array literal_blob literal_dataset literal_expression literal_hash literal_other literal_string literal_symbol source_list subselect_sql table_ref END ).split.map{|x| x.to_sym} |
# File lib/sequel/dataset/sql.rb, line 327
327: def self.def_append_methods(meths)
328: meths.each do |meth|
329: class_eval("def \#{meth}(*args, &block)\ns = ''\n\#{meth}_append(s, *args, &block)\ns\nend\n", __FILE__, __LINE__ + 1)
330: end
331: end
SQL fragment for BooleanConstants
# File lib/sequel/dataset/sql.rb, line 360
360: def boolean_constant_sql_append(sql, constant)
361: if (constant == true || constant == false) && !supports_where_true?
362: sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE)
363: else
364: literal_append(sql, constant)
365: end
366: end
SQL fragment for CaseExpression
# File lib/sequel/dataset/sql.rb, line 369
369: def case_expression_sql_append(sql, ce)
370: sql << CASE_OPEN
371: if ce.expression?
372: sql << SPACE
373: literal_append(sql, ce.expression)
374: end
375: w = CASE_WHEN
376: t = CASE_THEN
377: ce.conditions.each do |c,r|
378: sql << w
379: literal_append(sql, c)
380: sql << t
381: literal_append(sql, r)
382: end
383: sql << CASE_ELSE
384: literal_append(sql, ce.default)
385: sql << CASE_END
386: end
# File lib/sequel/dataset/sql.rb, line 402
402: def complex_expression_sql_append(sql, op, args)
403: case op
404: when *IS_OPERATORS
405: r = args.at(1)
406: if r.nil? || supports_is_true?
407: raise(InvalidOperation, 'Invalid argument used for IS operator') unless v = IS_LITERALS[r]
408: sql << PAREN_OPEN
409: literal_append(sql, args.at(0))
410: sql << SPACE << op.to_s << SPACE
411: sql << v << PAREN_CLOSE
412: elsif op == :IS
413: complex_expression_sql_append(sql, "=""=", args)
414: else
415: complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new("!=""!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)])
416: end
417: when :IN, "NOT IN""NOT IN"
418: cols = args.at(0)
419: vals = args.at(1)
420: col_array = true if cols.is_a?(Array)
421: if vals.is_a?(Array)
422: val_array = true
423: empty_val_array = vals == []
424: end
425: if col_array
426: if empty_val_array
427: if op == :IN
428: literal_append(sql, SQL::BooleanExpression.from_value_pairs(cols.to_a.map{|x| [x, x]}, :AND, true))
429: else
430: literal_append(sql, 1=>1)
431: end
432: elsif !supports_multiple_column_in?
433: if val_array
434: 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]})})
435: literal_append(sql, op == :IN ? expr : ~expr)
436: else
437: old_vals = vals
438: vals = vals.naked if vals.is_a?(Sequel::Dataset)
439: vals = vals.to_a
440: val_cols = old_vals.columns
441: complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
442: end
443: else
444: # If the columns and values are both arrays, use array_sql instead of
445: # literal so that if values is an array of two element arrays, it
446: # will be treated as a value list instead of a condition specifier.
447: sql << PAREN_OPEN
448: literal_append(sql, cols)
449: sql << SPACE << op.to_s << SPACE
450: if val_array
451: array_sql_append(sql, vals)
452: else
453: literal_append(sql, vals)
454: end
455: sql << PAREN_CLOSE
456: end
457: else
458: if empty_val_array
459: if op == :IN
460: literal_append(sql, SQL::BooleanExpression.from_value_pairs([[cols, cols]], :AND, true))
461: else
462: literal_append(sql, 1=>1)
463: end
464: else
465: sql << PAREN_OPEN
466: literal_append(sql, cols)
467: sql << SPACE << op.to_s << SPACE
468: literal_append(sql, vals)
469: sql << PAREN_CLOSE
470: end
471: end
472: when *TWO_ARITY_OPERATORS
473: sql << PAREN_OPEN
474: literal_append(sql, args.at(0))
475: sql << SPACE << op.to_s << SPACE
476: literal_append(sql, args.at(1))
477: sql << PAREN_CLOSE
478: when *N_ARITY_OPERATORS
479: sql << PAREN_OPEN
480: c = false
481: op_str = " #{op} "
482: args.each do |a|
483: sql << op_str if c
484: literal_append(sql, a)
485: c ||= true
486: end
487: sql << PAREN_CLOSE
488: when :NOT
489: sql << NOT_SPACE
490: literal_append(sql, args.at(0))
491: when :NOOP
492: literal_append(sql, args.at(0))
493: when 'B~''B~'
494: sql << TILDE
495: literal_append(sql, args.at(0))
496: when :extract
497: sql << EXTRACT << args.at(0).to_s << FROM
498: literal_append(sql, args.at(1))
499: sql << PAREN_CLOSE
500: else
501: raise(InvalidOperation, "invalid operator #{op}")
502: end
503: end
SQL fragment specifying a JOIN clause without ON or USING.
# File lib/sequel/dataset/sql.rb, line 522
522: def join_clause_sql_append(sql, jc)
523: table = jc.table
524: table_alias = jc.table_alias
525: table_alias = nil if table == table_alias
526: sql << SPACE << join_type_sql(jc.join_type) << SPACE
527: table_ref_append(sql, table)
528: as_sql_append(sql, table_alias) if table_alias
529: end
SQL fragment for the ordered expression, used in the ORDER BY clause.
# File lib/sequel/dataset/sql.rb, line 554
554: def ordered_expression_sql_append(sql, oe)
555: literal_append(sql, oe.expression)
556: sql << (oe.descending ? DESC : ASC)
557: case oe.nulls
558: when :first
559: sql << NULLS_FIRST
560: when :last
561: sql << NULLS_LAST
562: end
563: end
SQL fragment for a literal string with placeholders
# File lib/sequel/dataset/sql.rb, line 566
566: def placeholder_literal_string_sql_append(sql, pls)
567: args = pls.args
568: sql << PAREN_OPEN if pls.parens
569: if args.is_a?(Hash)
570: re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
571: if RUBY_VERSION >= '1.8.7'
572: str = pls.str
573: loop do
574: previous, q, str = str.partition(re)
575: sql << previous
576: literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
577: break if str.empty?
578: end
579: else
580: sql << pls.str.gsub(re){literal(args[$1.to_sym])}
581: end
582: else
583: i = -1
584: if RUBY_VERSION >= '1.8.7'
585: str = pls.str
586: loop do
587: previous, q, str = str.partition(QUESTION_MARK)
588: sql << previous
589: literal_append(sql, args.at(i+=1)) unless q.empty?
590: break if str.empty?
591: end
592: else
593: sql << pls.str.gsub(QUESTION_MARK_RE){literal(args.at(i+=1))}
594: end
595: end
596: sql << PAREN_CLOSE if pls.parens
597: end
SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table).
# File lib/sequel/dataset/sql.rb, line 601
601: def qualified_identifier_sql_append(sql, qcr)
602: case t = qcr.table
603: when Symbol, SQL::QualifiedIdentifier, SQL::Identifier
604: literal_append(sql, t)
605: else
606: quote_identifier_append(sql, t)
607: end
608: sql << DOT
609: case c = qcr.column
610: when Symbol, SQL::QualifiedIdentifier, SQL::Identifier
611: literal_append(sql, c)
612: else
613: quote_identifier_append(sql, c)
614: end
615: end
Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.
# File lib/sequel/dataset/sql.rb, line 620
620: def quote_identifier_append(sql, name)
621: if name.is_a?(LiteralString)
622: sql << name
623: else
624: name = name.value if name.is_a?(SQL::Identifier)
625: name = input_identifier(name)
626: if quote_identifiers?
627: quoted_identifier_append(sql, name)
628: else
629: sql << name
630: end
631: end
632: end
Separates the schema from the table and returns a string with them quoted (if quoting identifiers)
# File lib/sequel/dataset/sql.rb, line 636
636: def quote_schema_table_append(sql, table)
637: schema, table = schema_and_table(table)
638: if schema
639: quote_identifier_append(sql, schema)
640: sql << DOT
641: end
642: quote_identifier_append(sql, table)
643: end
This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).
# File lib/sequel/dataset/sql.rb, line 648
648: def quoted_identifier_append(sql, name)
649: sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE
650: end
Split the schema information from the table
# File lib/sequel/dataset/sql.rb, line 653
653: def schema_and_table(table_name)
654: sch = db.default_schema if db
655: case table_name
656: when Symbol
657: s, t, a = split_symbol(table_name)
658: [s||sch, t]
659: when SQL::QualifiedIdentifier
660: [table_name.table, table_name.column]
661: when SQL::Identifier
662: [sch, table_name.value]
663: when String
664: [sch, table_name]
665: else
666: raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
667: end
668: end
The SQL fragment for the given window‘s options.
# File lib/sequel/dataset/sql.rb, line 679
679: def window_sql_append(sql, opts)
680: raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
681: sql << PAREN_OPEN
682: window, part, order, frame = opts.values_at(:window, :partition, :order, :frame)
683: space = false
684: space_s = SPACE
685: if window
686: literal_append(sql, window)
687: space = true
688: end
689: if part
690: sql << space_s if space
691: sql << PARTITION_BY
692: expression_list_append(sql, Array(part))
693: space = true
694: end
695: if order
696: sql << space_s if space
697: sql << ORDER_BY_NS
698: expression_list_append(sql, Array(order))
699: space = true
700: end
701: case frame
702: when nil
703: # nothing
704: when :all
705: sql << space_s if space
706: sql << FRAME_ALL
707: when :rows
708: sql << space_s if space
709: sql << FRAME_ROWS
710: when String
711: sql << space_s if space
712: sql << frame
713: else
714: raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil"
715: end
716: sql << PAREN_CLOSE
717: end
These methods all execute the dataset‘s SQL on the database. They don‘t return modified datasets, so if used in a method chain they should be the last method called.
| ACTION_METHODS | = | (<<-METHS).split.map{|x| x.to_sym} << [] []= all avg count columns columns! delete each empty? fetch_rows first get import insert insert_multiple interval last map max min multi_insert range select_hash select_map select_order_map set single_record single_value sum to_csv to_hash truncate update METHS ).split.map{|x| x.to_sym} | Action methods defined by Sequel that execute code on the database. |
Inserts the given argument into the database. Returns self so it can be used safely when chaining:
DB[:items] << {:id=>0, :name=>'Zero'} << DB[:old_items].select(:id, name)
# File lib/sequel/dataset/actions.rb, line 23
23: def <<(arg)
24: insert(arg)
25: self
26: end
Returns the first record matching the conditions. Examples:
DB[:table][:id=>1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=1}
# File lib/sequel/dataset/actions.rb, line 32
32: def [](*conditions)
33: raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
34: first(*conditions)
35: end
Update all records matching the conditions with the values specified. Returns the number of rows affected.
DB[:table][:id=>1] = {:id=>2} # UPDATE table SET id = 2 WHERE id = 1
# => 1 # number of rows affected
# File lib/sequel/dataset/actions.rb, line 42
42: def []=(conditions, values)
43: filter(conditions).update(values)
44: end
Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.
DB[:table].all # SELECT * FROM table
# => [{:id=>1, ...}, {:id=>2, ...}, ...]
# Iterate over all rows in the table
DB[:table].all{|row| p row}
# File lib/sequel/dataset/actions.rb, line 54
54: def all(&block)
55: a = []
56: each{|r| a << r}
57: post_load(a)
58: a.each(&block) if block
59: a
60: end
Returns the average value for the given column.
DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1 # => 3
# File lib/sequel/dataset/actions.rb, line 66
66: def avg(column)
67: aggregate_dataset.get{avg(column)}
68: end
Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.
If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema.
DB[:table].columns # => [:id, :name]
# File lib/sequel/dataset/actions.rb, line 79
79: def columns
80: return @columns if @columns
81: ds = unfiltered.unordered.clone(:distinct => nil, :limit => 1, :offset=>nil)
82: ds.each{break}
83: @columns = ds.instance_variable_get(:@columns)
84: @columns || []
85: end
Returns the number of records in the dataset.
DB[:table].count # SELECT COUNT(*) AS count FROM table LIMIT 1 # => 3
# File lib/sequel/dataset/actions.rb, line 101
101: def count
102: aggregate_dataset.get{COUNT(:*){}.as(count)}.to_i
103: end
Deletes the records in the dataset. The returned value should be number of records deleted, but that is adapter dependent.
DB[:table].delete # DELETE * FROM table # => 3
# File lib/sequel/dataset/actions.rb, line 110
110: def delete(&block)
111: sql = delete_sql
112: if uses_returning?(:delete)
113: returning_fetch_rows(sql, &block)
114: else
115: execute_dui(sql)
116: end
117: end
Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.
DB[:table].each{|row| p row} # SELECT * FROM table
Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all instead of each for the outer queries, or use a separate thread or shard inside each:
# File lib/sequel/dataset/actions.rb, line 128
128: def each(&block)
129: if @opts[:graph]
130: graph_each(&block)
131: elsif row_proc = @row_proc
132: fetch_rows(select_sql){|r| yield row_proc.call(r)}
133: else
134: fetch_rows(select_sql, &block)
135: end
136: self
137: end
Returns true if no records exist in the dataset, false otherwise
DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1 # => false
# File lib/sequel/dataset/actions.rb, line 143
143: def empty?
144: get(Sequel::SQL::AliasedExpression.new(1, :one)).nil?
145: end
Executes a select query and fetches records, yielding each record to the supplied block. The yielded records should be hashes with symbol keys. This method should probably should not be called by user code, use each instead.
# File lib/sequel/dataset/actions.rb, line 151
151: def fetch_rows(sql)
152: raise NotImplemented, NOTIMPL_MSG
153: end
If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If no argument is passed, it returns the first matching record. If any other type of argument(s) is passed, it is given to filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything. 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("id = 3") # SELECT * FROM table WHERE (id = 3) LIMIT 1
# => {:id=>3}
DB[:table].first("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("id > ?", 4){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1
# => {:id=>5}
DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2
# => [{:id=>1}]
# File lib/sequel/dataset/actions.rb, line 185
185: def first(*args, &block)
186: ds = block ? filter(&block) : self
187:
188: if args.empty?
189: ds.single_record
190: else
191: args = (args.size == 1) ? args.first : args
192: if Integer === args
193: ds.limit(args).all
194: else
195: ds.filter(args).single_record
196: end
197: end
198: end
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) FROM table LIMIT 1
# => 6
# File lib/sequel/dataset/actions.rb, line 208
208: def get(column=nil, &block)
209: if column
210: raise(Error, ARG_BLOCK_ERROR_MSG) if block
211: select(column).single_value
212: else
213: select(&block).single_value
214: end
215: end
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. |
| :server : | Set the server/shard to use for the transaction and insert queries. |
| :slice : | Same as :commit_every, :commit_every takes precedence. |
# File lib/sequel/dataset/actions.rb, line 240
240: def import(columns, values, opts={})
241: return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
242:
243: return if values.empty?
244: raise(Error, IMPORT_ERROR_MSG) if columns.empty?
245: ds = opts[:server] ? server(opts[:server]) : self
246:
247: if slice_size = opts[:commit_every] || opts[:slice]
248: offset = 0
249: rows = []
250: while offset < values.length
251: rows << ds._import(columns, values[offset, slice_size], opts)
252: offset += slice_size
253: end
254: rows.flatten
255: else
256: ds._import(columns, values, opts)
257: end
258: end
Inserts values into the associated table. The returned value is generally the value of the primary key for the inserted row, but that is adapter dependent.
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 an values as values |
| single array : | Treats entries as values, with no columns |
| two arrays : | Treats first array as columns, second array as values |
| single Dataset : | Treats as an insert based on a selection from the dataset given, with no columns |
| array and dataset : | Treats as an insert based on a selection from the dataset given, with the columns given by the array. |
Examples:
DB[:items].insert
# INSERT INTO items DEFAULT VALUES
DB[:items].insert({})
# INSERT INTO items DEFAULT VALUES
DB[:items].insert([1,2,3])
# INSERT INTO items VALUES (1, 2, 3)
DB[:items].insert([:a, :b], [1,2])
# INSERT INTO items (a, b) VALUES (1, 2)
DB[:items].insert(:a => 1, :b => 2)
# INSERT INTO items (a, b) VALUES (1, 2)
DB[:items].insert(DB[:old_items])
# INSERT INTO items SELECT * FROM old_items
DB[:items].insert([:a, :b], DB[:old_items])
# INSERT INTO items (a, b) SELECT * FROM old_items
# File lib/sequel/dataset/actions.rb, line 295
295: def insert(*values, &block)
296: sql = insert_sql(*values)
297: if uses_returning?(:insert)
298: returning_fetch_rows(sql, &block)
299: else
300: execute_insert(sql)
301: end
302: end
Inserts multiple values. If a block is given it is invoked for each item in the given array before inserting it. See multi_insert as a possibly faster version that may be able to insert multiple records in one SQL statement (if supported by the database). Returns an array of primary keys of inserted rows.
DB[:table].insert_multiple([{:x=>1}, {:x=>2}])
# => [4, 5]
# INSERT INTO table (x) VALUES (1)
# INSERT INTO table (x) VALUES (2)
DB[:table].insert_multiple([{:x=>1}, {:x=>2}]){|row| row[:y] = row[:x] * 2}
# => [6, 7]
# INSERT INTO table (x, y) VALUES (1, 2)
# INSERT INTO table (x, y) VALUES (2, 4)
# File lib/sequel/dataset/actions.rb, line 319
319: def insert_multiple(array, &block)
320: if block
321: array.map{|i| insert(block.call(i))}
322: else
323: array.map{|i| insert(i)}
324: end
325: end
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(:id.desc).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
# => [{:id=>1}, {:id=>2}]
# File lib/sequel/dataset/actions.rb, line 346
346: def last(*args, &block)
347: raise(Error, 'No order specified') unless @opts[:order]
348: reverse.first(*args, &block)
349: end
Maps column values for each record in the dataset (if a column name 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'], ...]
# File lib/sequel/dataset/actions.rb, line 365
365: def map(column=nil, &block)
366: if column
367: raise(Error, ARG_BLOCK_ERROR_MSG) if block
368: return naked.map(column) if row_proc
369: if column.is_a?(Array)
370: super(){|r| r.values_at(*column)}
371: else
372: super(){|r| r[column]}
373: end
374: else
375: super(&block)
376: end
377: end
Returns the maximum value for the given column.
DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1 # => 10
# File lib/sequel/dataset/actions.rb, line 383
383: def max(column)
384: aggregate_dataset.get{max(column)}
385: end
Returns the minimum value for the given column.
DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1 # => 1
# File lib/sequel/dataset/actions.rb, line 391
391: def min(column)
392: aggregate_dataset.get{min(column)}
393: end
This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:
DB[:table].multi_insert([{:x => 1}, {:x => 2}])
# INSERT INTO table (x) VALUES (1)
# INSERT INTO table (x) VALUES (2)
Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.
This respects the same options as import.
# File lib/sequel/dataset/actions.rb, line 407
407: def multi_insert(hashes, opts={})
408: return if hashes.empty?
409: columns = hashes.first.keys
410: import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
411: end
Returns a Range instance made from the minimum and maximum values for the given column.
DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1 # => 1..10
# File lib/sequel/dataset/actions.rb, line 418
418: def range(column)
419: if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first
420: (r[:v1]..r[:v2])
421: end
422: end
Returns a hash with key_column values as keys and value_column values as values. Similar to to_hash, but only selects the two columns.
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'], ...}
# File lib/sequel/dataset/actions.rb, line 435
435: def select_hash(key_column, value_column)
436: if key_column.is_a?(Array)
437: if value_column.is_a?(Array)
438: select(*(key_column + value_column)).to_hash(key_column.map{|c| hash_key_symbol(c)}, value_column.map{|c| hash_key_symbol(c)})
439: else
440: select(*(key_column + [value_column])).to_hash(key_column.map{|c| hash_key_symbol(c)}, hash_key_symbol(value_column))
441: end
442: elsif value_column.is_a?(Array)
443: select(key_column, *value_column).to_hash(hash_key_symbol(key_column), value_column.map{|c| hash_key_symbol(c)})
444: else
445: select(key_column, value_column).to_hash(hash_key_symbol(key_column), hash_key_symbol(value_column))
446: end
447: end
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'], ...]
# File lib/sequel/dataset/actions.rb, line 465
465: def select_map(column=nil, &block)
466: _select_map(column, false, &block)
467: end
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'], ...]
# File lib/sequel/dataset/actions.rb, line 482
482: def select_order_map(column=nil, &block)
483: _select_map(column, true, &block)
484: end
Returns a string in CSV format containing the dataset records. By default the CSV representation includes the column titles in the first line. You can turn that off by passing false as the include_column_titles argument.
This does not use a CSV library or handle quoting of values in any way. If any values in any of the rows could include commas or line endings, you shouldn‘t use this.
puts DB[:table].to_csv # SELECT * FROM table # id,name # 1,Jim # 2,Bob
# File lib/sequel/dataset/actions.rb, line 530
530: def to_csv(include_column_titles = true)
531: n = naked
532: cols = n.columns
533: csv = ''
534: csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles
535: n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"}
536: csv
537: end
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].to_hash(:id, :name) # SELECT * FROM table
# {1=>'Jim', 2=>'Bob', ...}
DB[:table].to_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].to_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...}
DB[:table].to_hash([:id, :name]) # SELECT * FROM table
# {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob'=>{:id=>2, :name=>'Bob'}, ...}
# File lib/sequel/dataset/actions.rb, line 558
558: def to_hash(key_column, value_column = nil)
559: h = {}
560: if value_column
561: return naked.to_hash(key_column, value_column) if row_proc
562: if value_column.is_a?(Array)
563: if key_column.is_a?(Array)
564: each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
565: else
566: each{|r| h[r[key_column]] = r.values_at(*value_column)}
567: end
568: else
569: if key_column.is_a?(Array)
570: each{|r| h[r.values_at(*key_column)] = r[value_column]}
571: else
572: each{|r| h[r[key_column]] = r[value_column]}
573: end
574: end
575: elsif key_column.is_a?(Array)
576: each{|r| h[r.values_at(*key_column)] = r}
577: else
578: each{|r| h[r[key_column]] = r}
579: end
580: h
581: end
Truncates the dataset. Returns nil.
DB[:table].truncate # TRUNCATE table # => nil
# File lib/sequel/dataset/actions.rb, line 587
587: def truncate
588: execute_ddl(truncate_sql)
589: end
Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent. values should 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=>:x+1, :y=>0) # UPDATE table SET x = (x + 1), y = 0 # => 10
# File lib/sequel/dataset/actions.rb, line 601
601: def update(values={}, &block)
602: sql = update_sql(values)
603: if uses_returning?(:update)
604: returning_fetch_rows(sql, &block)
605: else
606: execute_dui(sql)
607: end
608: end
Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately.
# File lib/sequel/dataset/actions.rb, line 615
615: def _import(columns, values, opts)
616: trans_opts = opts.merge(:server=>@opts[:server])
617: if opts[:return] == :primary_key
618: @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
619: else
620: stmts = multi_insert_sql(columns, values)
621: @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
622: end
623: end
Return an array of arrays of values given by the symbols in ret_cols.
# File lib/sequel/dataset/actions.rb, line 626
626: def _select_map_multiple(ret_cols)
627: map{|r| r.values_at(*ret_cols)}
628: end
| MUTATION_METHODS | = | QUERY_METHODS | All methods that should have a ! method added that modifies the receiver. |
| identifier_input_method | [W] | Set the method to call on identifiers going into the database for this dataset |
| identifier_output_method | [W] | Set the method to call on identifiers coming the database for this dataset |
| quote_identifiers | [W] | Whether to quote identifiers for this dataset |
| row_proc | [RW] | 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. |
Setup mutation (e.g. filter!) methods. These operate the same as the non-! methods, but replace the options of the current dataset with the options of the resulting dataset.
# File lib/sequel/dataset/mutation.rb, line 14
14: def self.def_mutation_method(*meths)
15: meths.each do |meth|
16: class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__)
17: end
18: end
On some adapters, these use native prepared statements and bound variables, on others support is emulated. For details, see the "Prepared Statements/Bound Variables" guide.
| PREPARED_ARG_PLACEHOLDER | = | LiteralString.new('?').freeze |
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].filter(:id=>:$id).bind(:id=>1).call(:first)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 200
200: def bind(bind_vars={})
201: clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars)
202: end
For the given type (:select, :first, :insert, :insert_select, :update, or :delete), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.
DB[:table].filter(:id=>:$id).call(:first, :id=>1)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
# File lib/sequel/dataset/prepared_statements.rb, line 211
211: def call(type, bind_variables={}, *values, &block)
212: prepare(type, nil, *values).call(bind_variables, &block)
213: end
Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement. While name defaults to nil, it should always be provided as a symbol for the name of the prepared statement, as some databases require that prepared statements have names.
This returns a clone of the dataset extended with PreparedStatementMethods, which you can call with the hash of bind variables to use. The prepared statement is also stored in the associated database, where it can be called by name. The following usage is identical:
ps = DB[:table].filter(:name=>:$name).prepare(:first, :select_by_name)
ps.call(:name=>'Blah')
# SELECT * FROM table WHERE name = ? -- ('Blah')
# => {:id=>1, :name=>'Blah'}
DB.call(:select_by_name, :name=>'Blah') # Same thing
# File lib/sequel/dataset/prepared_statements.rb, line 233
233: def prepare(type, name=nil, *values)
234: ps = to_prepared_statement(type, values)
235: db.prepared_statements[name] = ps if name
236: ps
237: end
Return a cloned copy of the current dataset extended with PreparedStatementMethods, setting the type and modify values.
# File lib/sequel/dataset/prepared_statements.rb, line 243
243: def to_prepared_statement(type, values=nil)
244: ps = bind
245: ps.extend(PreparedStatementMethods)
246: ps.orig_dataset = self
247: ps.prepared_type = type
248: ps.prepared_modify_values = values
249: ps
250: end
Dataset graphing changes the dataset to yield hashes where keys are table name symbols and values are hashes representing the columns related to that table. All of these methods return modified copies of the receiver.
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_more when graphing). See set_graph_aliases.
DB[:table].add_graph_aliases(:some_alias=>[:table, :column])
# SELECT ..., table.column AS some_alias
# => {:table=>{:column=>some_alias_value, ...}, ...}
# File lib/sequel/dataset/graph.rb, line 17
17: def add_graph_aliases(graph_aliases)
18: columns, graph_aliases = graph_alias_columns(graph_aliases)
19: ds = select_more(*columns)
20: ds.opts[:graph_aliases] = (ds.opts[:graph_aliases] || (ds.opts[:graph][:column_aliases] rescue {}) || {}).merge(graph_aliases)
21: ds
22: end
Allows you to join multiple datasets/tables and have the result set split into component tables.
This differs from the usual usage of join, which returns the result set as a single hash. For example:
# CREATE TABLE artists (id INTEGER, name TEXT);
# CREATE TABLE albums (id INTEGER, name TEXT, artist_id INTEGER);
DB[:artists].left_outer_join(:albums, :artist_id=>:id).first
#=> {:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}
DB[:artists].graph(:albums, :artist_id=>:id).first
#=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>{:id=>albums.id, :name=>albums.name, :artist_id=>albums.artist_id}}
Using a join such as left_outer_join, the attribute names that are shared between the tables are combined in the single return hash. You can get around that by using select with correct aliases for all of the columns, but it is simpler to use graph and have the result set split for you. In addition, graph respects any row_proc of the current dataset and the datasets you use with graph.
If you are graphing a table and all columns for that table are nil, this indicates that no matching rows existed in the table, so graph will return nil instead of a hash with all nil values:
# If the artist doesn't have any albums
DB[:artists].graph(:albums, :artist_id=>:id).first
=> {:artists=>{:id=>artists.id, :name=>artists.name}, :albums=>nil}
Arguments:
| dataset : | Can be a symbol (specifying a table), another dataset, or an object that responds to dataset and returns a symbol or a dataset |
| 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_type : | The type of join to use (passed to join_table). Defaults to :left_outer. |
| :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 the alias (or table) name is used more than once. |
# File lib/sequel/dataset/graph.rb, line 74
74: def graph(dataset, join_conditions = nil, options = {}, &block)
75: # Allow the use of a model, dataset, or symbol as the first argument
76: # Find the table name/dataset based on the argument
77: dataset = dataset.dataset if dataset.respond_to?(:dataset)
78: table_alias = options[:table_alias]
79: case dataset
80: when Symbol
81: table = dataset
82: dataset = @db[dataset]
83: table_alias ||= table
84: when ::Sequel::Dataset
85: if dataset.simple_select_all?
86: table = dataset.opts[:from].first
87: table_alias ||= table
88: else
89: table = dataset
90: table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
91: end
92: else
93: raise Error, "The dataset argument should be a symbol, dataset, or model"
94: end
95:
96: # Raise Sequel::Error with explanation that the table alias has been used
97: raise_alias_error = lambda do
98: raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
99: "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}")
100: end
101:
102: # Only allow table aliases that haven't been used
103: raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
104:
105: # Use a from_self if this is already a joined table
106: ds = (!@opts[:graph] && (@opts[:from].length > 1 || @opts[:join])) ? from_self(:alias=>options[:from_self_alias] || first_source) : self
107:
108: # Join the table early in order to avoid cloning the dataset twice
109: ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>options[:implicit_qualifier], &block)
110: opts = ds.opts
111:
112: # Whether to include the table in the result set
113: add_table = options[:select] == false ? false : true
114: # Whether to add the columns to the list of column aliases
115: add_columns = !ds.opts.include?(:graph_aliases)
116:
117: # Setup the initial graph data structure if it doesn't exist
118: if graph = opts[:graph]
119: opts[:graph] = graph = graph.dup
120: select = opts[:select].dup
121: [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
122: else
123: master = alias_symbol(ds.first_source_alias)
124: raise_alias_error.call if master == table_alias
125: # Master hash storing all .graph related information
126: graph = opts[:graph] = {}
127: # Associates column aliases back to tables and columns
128: column_aliases = graph[:column_aliases] = {}
129: # Associates table alias (the master is never aliased)
130: table_aliases = graph[:table_aliases] = {master=>self}
131: # Keep track of the alias numbers used
132: ca_num = graph[:column_alias_num] = Hash.new(0)
133: # All columns in the master table are never
134: # aliased, but are not included if set_graph_aliases
135: # has been used.
136: if add_columns
137: if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll)))
138: select = select.each do |sel|
139: column = case sel
140: when Symbol
141: _, c, a = split_symbol(sel)
142: (a || c).to_sym
143: when SQL::Identifier
144: sel.value.to_sym
145: when SQL::QualifiedIdentifier
146: column = sel.column
147: column = column.value if column.is_a?(SQL::Identifier)
148: column.to_sym
149: when SQL::AliasedExpression
150: column = sel.aliaz
151: column = column.value if column.is_a?(SQL::Identifier)
152: column.to_sym
153: else
154: raise Error, "can't figure out alias to use for graphing for #{sel.inspect}"
155: end
156: column_aliases[column] = [master, column]
157: end
158: select = qualified_expression(select, master)
159: else
160: select = columns.map do |column|
161: column_aliases[column] = [master, column]
162: SQL::QualifiedIdentifier.new(master, column)
163: end
164: end
165: end
166: end
167:
168: # Add the table alias to the list of aliases
169: # Even if it isn't been used in the result set,
170: # we add a key for it with a nil value so we can check if it
171: # is used more than once
172: table_aliases = graph[:table_aliases]
173: table_aliases[table_alias] = add_table ? dataset : nil
174:
175: # Add the columns to the selection unless we are ignoring them
176: if add_table && add_columns
177: column_aliases = graph[:column_aliases]
178: ca_num = graph[:column_alias_num]
179: # Which columns to add to the result set
180: cols = options[:select] || dataset.columns
181: # If the column hasn't been used yet, don't alias it.
182: # If it has been used, try table_column.
183: # If that has been used, try table_column_N
184: # using the next value of N that we know hasn't been
185: # used
186: cols.each do |column|
187: col_alias, identifier = if column_aliases[column]
188: column_alias = "#{table_alias}_#{column}""#{table_alias}_#{column}"
189: if column_aliases[column_alias]
190: column_alias_num = ca_num[column_alias]
191: column_alias = "#{column_alias}_#{column_alias_num}""#{column_alias}_#{column_alias_num}"
192: ca_num[column_alias] += 1
193: end
194: [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias, column), column_alias)]
195: else
196: ident = SQL::QualifiedIdentifier.new(table_alias, column)
197: [column, ident]
198: end
199: column_aliases[col_alias] = [table_alias, column]
200: select.push(identifier)
201: end
202: end
203: add_columns ? ds.select(*select) : ds
204: end
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 ...
# => {:artists=>{:name=>artists.name}, :albums=>{:name=>albums.name, :fourtwo=>42}}
# File lib/sequel/dataset/graph.rb, line 230
230: def set_graph_aliases(graph_aliases)
231: columns, graph_aliases = graph_alias_columns(graph_aliases)
232: ds = select(*columns)
233: ds.opts[:graph_aliases] = graph_aliases
234: ds
235: end
These methods all return modified copies of the receiver.
| COLUMN_CHANGE_OPTS | = | [:select, :sql, :from, :join].freeze | The dataset options that require the removal of cached columns if changed. | |
| NON_SQL_OPTIONS | = | [:server, :defaults, :overrides, :graph, :eager_graph, :graph_aliases] | Which options don‘t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table. | |
| CONDITIONED_JOIN_TYPES | = | [:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left] | 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. | |
| UNCONDITIONED_JOIN_TYPES | = | [:natural, :natural_left, :natural_right, :natural_full, :cross] | These symbols have _join methods created (e.g. natural_join) that call join_table with the symbol. They only accept a single table argument which is passed to join_table, and they raise an error if called with a block. | |
| JOIN_METHODS | = | (CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table] | All methods that return modified datasets with a joined table added. | |
| QUERY_METHODS | = | (<<-METHS).split.map{|x| x.to_sym} + JOIN_METHODS add_graph_aliases and distinct except exclude exclude_having exclude_where filter for_update from from_self graph grep group group_and_count group_by having intersect invert limit lock_style naked or order order_append order_by order_more order_prepend paginate qualify query reverse reverse_order select select_all select_append select_group select_more server set_defaults set_graph_aliases set_overrides unfiltered ungraphed ungrouped union unlimited unordered where with with_recursive with_sql METHS ).split.map{|x| x.to_sym} + JOIN_METHODS | Methods that return modified datasets |
Adds an further filter to an existing filter using AND. If no filter exists an error is raised. This method is identical to filter except it expects an existing filter.
DB[:table].filter(:a).and(:b) # SELECT * FROM table WHERE a AND b
# File lib/sequel/dataset/query.rb, line 46
46: def and(*cond, &block)
47: raise(InvalidOperation, "No existing filter found.") unless @opts[:having] || @opts[:where]
48: filter(*cond, &block)
49: end
Returns a new clone of the dataset with 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.
# File lib/sequel/dataset/query.rb, line 55
55: def clone(opts = {})
56: c = super()
57: c.opts = @opts.merge(opts)
58: c.instance_variable_set(:@columns, nil) if opts.keys.any?{|o| COLUMN_CHANGE_OPTS.include?(o)}
59: c
60: end
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. 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
# File lib/sequel/dataset/query.rb, line 71
71: def distinct(*args)
72: raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
73: clone(:distinct => args)
74: end
Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation if the operation is not supported. Options:
| :alias : | Use the given value as the from_self alias |
| :all : | Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur |
| :from_self : | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].except(DB[:other_items]) # SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1 DB[:items].except(DB[:other_items], :all=>true, :from_self=>false) # SELECT * FROM items EXCEPT ALL SELECT * FROM other_items DB[:items].except(DB[:other_items], :alias=>:i) # SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 93
93: def except(dataset, opts={})
94: opts = {:all=>opts} unless opts.is_a?(Hash)
95: raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
96: raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
97: compound_clone(:except, dataset, opts)
98: end
Performs the inverse of Dataset#filter. 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))
# File lib/sequel/dataset/query.rb, line 108
108: def exclude(*cond, &block)
109: _filter_or_exclude(true, @opts[:having] ? :having : :where, *cond, &block)
110: end
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)
# File lib/sequel/dataset/query.rb, line 116
116: def exclude_having(*cond, &block)
117: _filter_or_exclude(true, :having, *cond, &block)
118: end
Inverts the given conditions and adds them to the WHERE clause.
DB[:items].select_group(:name).exclude_where(:category => 'software')
# SELECT * FROM items WHERE (category != 'software')
DB[:items].select_group(:name).
exclude_having{count(name) < 2}.
exclude_where(:category => 'software')
# SELECT name FROM items WHERE (category != 'software')
# GROUP BY name HAVING (count(name) >= 2)
# File lib/sequel/dataset/query.rb, line 130
130: def exclude_where(*cond, &block)
131: _filter_or_exclude(true, :where, *cond, &block)
132: end
Returns a copy of the dataset with the given conditions imposed upon it. If the query already has a HAVING clause, then the conditions are imposed in the HAVING clause. If not, then they are imposed in the WHERE clause.
filter accepts the following argument types:
filter also takes 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].filter(:id => 3)
# SELECT * FROM items WHERE (id = 3)
DB[:items].filter('price < ?', 100)
# SELECT * FROM items WHERE price < 100
DB[:items].filter([[:id, (1,2,3)], [:id, 0..10]])
# SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))
DB[:items].filter('price < 100')
# SELECT * FROM items WHERE price < 100
DB[:items].filter(:active)
# SELECT * FROM items WHERE :active
DB[:items].filter{price < 100}
# SELECT * FROM items WHERE (price < 100)
Multiple filter calls can be chained for scoping:
software = dataset.filter(:category => 'software').filter{price < 100}
# SELECT * FROM items WHERE ((category = 'software') AND (price < 100))
See the the "Dataset Filtering" guide for more examples and details.
# File lib/sequel/dataset/query.rb, line 186
186: def filter(*cond, &block)
187: _filter(@opts[:having] ? :having : :where, *cond, &block)
188: end
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.
DB[:items].from # SQL: SELECT * DB[:items].from(:blah) # SQL: SELECT * FROM blah DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo
# File lib/sequel/dataset/query.rb, line 204
204: def from(*source)
205: table_alias_num = 0
206: sources = []
207: ctes = nil
208: source.each do |s|
209: case s
210: when Hash
211: s.each{|k,v| sources << SQL::AliasedExpression.new(k,v)}
212: when Dataset
213: if hoist_cte?(s)
214: ctes ||= []
215: ctes += s.opts[:with]
216: s = s.clone(:with=>nil)
217: end
218: sources << SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
219: when Symbol
220: sch, table, aliaz = split_symbol(s)
221: if aliaz
222: s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
223: sources << SQL::AliasedExpression.new(s, aliaz.to_sym)
224: else
225: sources << s
226: end
227: else
228: sources << s
229: end
230: end
231: o = {:from=>sources.empty? ? nil : sources}
232: o[:with] = (opts[:with] || []) + ctes if ctes
233: o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
234: clone(o)
235: end
Returns a dataset selecting from the current dataset. Supplying the :alias option controls the alias of the result.
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
# File lib/sequel/dataset/query.rb, line 248
248: def from_self(opts={})
249: fs = {}
250: @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)}
251: clone(fs).from(opts[:alias] ? as(opts[:alias]) : self)
252: end
Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions (which are only supported on MySQL and PostgreSQL). 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%') dataset.grep([:a, :b], %w'%test% foo') # SELECT * FROM items WHERE ((a LIKE '%test%') OR (a LIKE 'foo') OR (b LIKE '%test%') OR (b LIKE 'foo')) dataset.grep([:a, :b], %w'%foo% %bar%', :all_patterns=>true) # SELECT * FROM a WHERE (((a LIKE '%foo%') OR (b LIKE '%foo%')) AND ((a LIKE '%bar%') OR (b LIKE '%bar%'))) dataset.grep([:a, :b], %w'%foo% %bar%', :all_columns=>true) # SELECT * FROM a WHERE (((a LIKE '%foo%') OR (a LIKE '%bar%')) AND ((b LIKE '%foo%') OR (b LIKE '%bar%'))) dataset.grep([:a, :b], %w'%foo% %bar%', :all_patterns=>true, :all_columns=>true) # SELECT * FROM a WHERE ((a LIKE '%foo%') AND (b LIKE '%foo%') AND (a LIKE '%bar%') AND (b LIKE '%bar%'))
# File lib/sequel/dataset/query.rb, line 285
285: def grep(columns, patterns, opts={})
286: if opts[:all_patterns]
287: conds = Array(patterns).map do |pat|
288: SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
289: end
290: filter(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds))
291: else
292: conds = Array(columns).map do |c|
293: SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
294: end
295: filter(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds))
296: end
297: end
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 filter.
DB[:items].group(:id) # SELECT * FROM items GROUP BY id
DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name
DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
# File lib/sequel/dataset/query.rb, line 306
306: def group(*columns, &block)
307: virtual_row_columns(columns, block)
308: clone(:group => (columns.compact.empty? ? nil : columns))
309: end
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 filter.
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(:first_name___name).all
# SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name
# => [{:name=>'a', :count=>1}, ...]
DB[:items].group_and_count{substr(first_name, 1, 1).as(initial)}.all
# SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1)
# => [{:initial=>'a', :count=>1}, ...]
# File lib/sequel/dataset/query.rb, line 337
337: def group_and_count(*columns, &block)
338: select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT)
339: end
Adds the appropriate CUBE syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 342
342: def group_cube
343: raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
344: clone(:group_options=>:cube)
345: end
Adds the appropriate ROLLUP syntax to GROUP BY.
# File lib/sequel/dataset/query.rb, line 348
348: def group_rollup
349: raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
350: clone(:group_options=>:rollup)
351: end
Returns a copy of the dataset with the HAVING conditions changed. See filter for argument types.
DB[:items].group(:sum).having(:sum=>10) # SELECT * FROM items GROUP BY sum HAVING (sum = 10)
# File lib/sequel/dataset/query.rb, line 357
357: def having(*cond, &block)
358: _filter(:having, *cond, &block)
359: end
Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation if the operation is not supported. Options:
| :alias : | Use the given value as the from_self alias |
| :all : | Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur |
| :from_self : | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].intersect(DB[:other_items]) # SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1 DB[:items].intersect(DB[:other_items], :all=>true, :from_self=>false) # SELECT * FROM items INTERSECT ALL SELECT * FROM other_items DB[:items].intersect(DB[:other_items], :alias=>:i) # SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 378
378: def intersect(dataset, opts={})
379: opts = {:all=>opts} unless opts.is_a?(Hash)
380: raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
381: raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
382: compound_clone(:intersect, dataset, opts)
383: end
Inverts the current filter.
DB[:items].filter(:category => 'software').invert # SELECT * FROM items WHERE (category != 'software') DB[:items].filter(:category => 'software', :id=>3).invert # SELECT * FROM items WHERE ((category != 'software') OR (id != 3))
# File lib/sequel/dataset/query.rb, line 392
392: def invert
393: having, where = @opts[:having], @opts[:where]
394: raise(Error, "No current filter") unless having || where
395: o = {}
396: o[:having] = SQL::BooleanExpression.invert(having) if having
397: o[:where] = SQL::BooleanExpression.invert(where) if where
398: clone(o)
399: end
Alias of inner_join
# File lib/sequel/dataset/query.rb, line 402
402: def join(*args, &block)
403: inner_join(*args, &block)
404: end
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:
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, :b___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|
(:d.qualify(ta) > :e.qualify(jta)) & {:f.qualify(ta)=>DB.from(js.first.table).select(:g)}
end
# SELECT * FROM a NATURAL JOIN b INNER JOIN c
# ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
# File lib/sequel/dataset/query.rb, line 457
457: def join_table(type, table, expr=nil, options={}, &block)
458: if hoist_cte?(table)
459: s, ds = hoist_cte(table)
460: return s.join_table(type, ds, expr, options, &block)
461: end
462:
463: using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
464: if using_join && !supports_join_using?
465: h = {}
466: expr.each{|s| h[s] = s}
467: return join_table(type, table, h, options)
468: end
469:
470: case options
471: when Hash
472: table_alias = options[:table_alias]
473: last_alias = options[:implicit_qualifier]
474: when Symbol, String, SQL::Identifier
475: table_alias = options
476: last_alias = nil
477: else
478: raise Error, "invalid options format for join_table: #{options.inspect}"
479: end
480:
481: if Dataset === table
482: if table_alias.nil?
483: table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
484: table_alias = dataset_alias(table_alias_num)
485: end
486: table_name = table_alias
487: else
488: table = table.table_name if table.respond_to?(:table_name)
489: table, implicit_table_alias = split_alias(table)
490: table_alias ||= implicit_table_alias
491: table_name = table_alias || table
492: end
493:
494: join = if expr.nil? and !block
495: SQL::JoinClause.new(type, table, table_alias)
496: elsif using_join
497: raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
498: SQL::JoinUsingClause.new(expr, type, table, table_alias)
499: else
500: last_alias ||= @opts[:last_joined_table] || first_source_alias
501: if Sequel.condition_specifier?(expr)
502: expr = expr.collect do |k, v|
503: k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
504: v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
505: [k,v]
506: end
507: expr = SQL::BooleanExpression.from_value_pairs(expr)
508: end
509: if block
510: expr2 = yield(table_name, last_alias, @opts[:join] || [])
511: expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
512: end
513: SQL::JoinOnClause.new(expr, type, table, table_alias)
514: end
515:
516: opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name}
517: opts[:num_dataset_sources] = table_alias_num if table_alias_num
518: clone(opts)
519: end
If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.
DB[:items].limit(10) # SELECT * FROM items LIMIT 10 DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20 DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10 DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10 DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
# File lib/sequel/dataset/query.rb, line 538
538: def limit(l, o = nil)
539: return from_self.limit(l, o) if @opts[:sql]
540:
541: if Range === l
542: o = l.first
543: l = l.last - l.first + (l.exclude_end? ? 0 : 1)
544: end
545: l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
546: if l.is_a?(Integer)
547: raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
548: end
549: opts = {:limit => l}
550: if o
551: o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
552: if o.is_a?(Integer)
553: raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
554: end
555: opts[:offset] = o
556: end
557: clone(opts)
558: end
Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. Otherwise, a symbol may be used for database independent locking. Currently :update is respected by most databases, and :share is supported by some.
DB[:items].lock_style('FOR SHARE') # SELECT * FROM items FOR SHARE
# File lib/sequel/dataset/query.rb, line 566
566: def lock_style(style)
567: clone(:lock => style)
568: end
Returns a cloned dataset without a row_proc.
ds = DB[:items]
ds.row_proc = proc{|r| r.invert}
ds.all # => [{2=>:id}]
ds.naked.all # => [{:id=>2}]
# File lib/sequel/dataset/query.rb, line 576
576: def naked
577: ds = clone
578: ds.row_proc = nil
579: ds
580: end
Adds an alternate filter to an existing filter using OR. If no filter exists an Error is raised.
DB[:items].filter(:a).or(:b) # SELECT * FROM items WHERE a OR b
# File lib/sequel/dataset/query.rb, line 586
586: def or(*cond, &block)
587: clause = (@opts[:having] ? :having : :where)
588: raise(InvalidOperation, "No existing filter found.") unless @opts[clause]
589: cond = cond.first if cond.size == 1
590: clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block)))
591: end
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 filter.
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('a + b'.lit) # SELECT * FROM items ORDER BY a + b
DB[:items].order(:a + :b) # SELECT * FROM items ORDER BY (a + b)
DB[:items].order(:name.desc) # SELECT * FROM items ORDER BY name DESC
DB[:items].order(:name.asc(:nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
DB[:items].order(nil) # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 607
607: def order(*columns, &block)
608: virtual_row_columns(columns, block)
609: clone(:order => (columns.compact.empty?) ? nil : columns)
610: end
Alias of order_more, for naming consistency with order_prepend.
# File lib/sequel/dataset/query.rb, line 613
613: def order_append(*columns, &block)
614: order_more(*columns, &block)
615: end
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_more(:b) # SELECT * FROM items ORDER BY a, b
# File lib/sequel/dataset/query.rb, line 627
627: def order_more(*columns, &block)
628: columns = @opts[:order] + columns if @opts[:order]
629: order(*columns, &block)
630: end
Returns a copy of the dataset with the order columns added to the beginning of the existing order.
DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
# File lib/sequel/dataset/query.rb, line 637
637: def order_prepend(*columns, &block)
638: ds = order(*columns, &block)
639: @opts[:order] ? ds.order_more(*@opts[:order]) : ds
640: end
Qualify to the given table, or first source if no table is given.
DB[:items].filter(:id=>1).qualify # SELECT items.* FROM items WHERE (items.id = 1) DB[:items].filter(:id=>1).qualify(:i) # SELECT i.* FROM items WHERE (i.id = 1)
# File lib/sequel/dataset/query.rb, line 649
649: def qualify(table=first_source)
650: qualify_to(table)
651: end
Return a copy of the dataset with unqualified identifiers in the SELECT, WHERE, GROUP, HAVING, and ORDER clauses qualified by the given table. If no columns are currently selected, select all columns of the given table.
DB[:items].filter(:id=>1).qualify_to(:i) # SELECT i.* FROM items WHERE (i.id = 1)
# File lib/sequel/dataset/query.rb, line 660
660: def qualify_to(table)
661: o = @opts
662: return clone if o[:sql]
663: h = {}
664: (o.keys & QUALIFY_KEYS).each do |k|
665: h[k] = qualified_expression(o[k], table)
666: end
667: h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty?
668: clone(h)
669: end
Qualify the dataset to its current first source. This is useful if you have unqualified identifiers in the query that all refer to the first source, and you want to join to another table which has columns with the same name as columns in the current dataset. See qualify_to.
DB[:items].filter(:id=>1).qualify_to_first_source # SELECT items.* FROM items WHERE (items.id = 1)
# File lib/sequel/dataset/query.rb, line 679
679: def qualify_to_first_source
680: qualify_to(first_source)
681: end
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
# File lib/sequel/dataset/query.rb, line 691
691: def returning(*values)
692: clone(:returning=>values)
693: end
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].order(:id).reverse # SELECT * FROM items ORDER BY id DESC DB[:items].order(:id).reverse(:name.asc) # SELECT * FROM items ORDER BY name ASC
# File lib/sequel/dataset/query.rb, line 701
701: def reverse(*order)
702: order(*invert_order(order.empty? ? @opts[:order] : order))
703: end
Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to filter.
DB[:items].select(:a) # SELECT a FROM items
DB[:items].select(:a, :b) # SELECT a, b FROM items
DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
# File lib/sequel/dataset/query.rb, line 717
717: def select(*columns, &block)
718: virtual_row_columns(columns, block)
719: m = []
720: columns.each do |i|
721: i.is_a?(Hash) ? m.concat(i.map{|k, v| SQL::AliasedExpression.new(k,v)}) : m << i
722: end
723: clone(:select => m)
724: end
Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.
DB[:items].select(:a).select_all # SELECT * FROM items DB[:items].select_all(:items) # SELECT items.* FROM items DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
# File lib/sequel/dataset/query.rb, line 733
733: def select_all(*tables)
734: if tables.empty?
735: clone(:select => nil)
736: else
737: select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)})
738: end
739: end
Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.
DB[:items].select(:a).select(:b) # SELECT b FROM items DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items DB[:items].select_append(:b) # SELECT *, b FROM items
# File lib/sequel/dataset/query.rb, line 748
748: def select_append(*columns, &block)
749: cur_sel = @opts[:select]
750: if !cur_sel || cur_sel.empty?
751: unless supports_select_all_and_column?
752: return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block)
753: end
754: cur_sel = [WILDCARD]
755: end
756: select(*(cur_sel + columns), &block)
757: end
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 filter.
DB[:items].select_group(:a, :b)
# SELECT a, b FROM items GROUP BY a, b
DB[:items].select_group(:c___a){f(c2)}
# SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
# File lib/sequel/dataset/query.rb, line 768
768: def select_group(*columns, &block)
769: virtual_row_columns(columns, block)
770: select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
771: end
Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected it will just select the columns given.
DB[:items].select(:a).select(:b) # SELECT b FROM items DB[:items].select(:a).select_more(:b) # SELECT a, b FROM items DB[:items].select_more(:b) # SELECT b FROM items
# File lib/sequel/dataset/query.rb, line 780
780: def select_more(*columns, &block)
781: columns = @opts[:select] + columns if @opts[:select]
782: select(*columns, &block)
783: end
Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.
DB[:items].all # Uses the :read_only or :default server DB[:items].delete # Uses the :default server DB[:items].server(:blah).delete # Uses the :blah server
# File lib/sequel/dataset/query.rb, line 794
794: def server(servr)
795: clone(:server=>servr)
796: end
Set the default values for insert and update statements. The values hash passed to insert or update are merged into this hash, so any values in the hash passed to insert or update will override values passed to this method.
DB[:items].set_defaults(:a=>'a', :c=>'c').insert(:a=>'d', :b=>'b')
# INSERT INTO items (a, c, b) VALUES ('d', 'c', 'b')
# File lib/sequel/dataset/query.rb, line 804
804: def set_defaults(hash)
805: clone(:defaults=>(@opts[:defaults]||{}).merge(hash))
806: end
Set values that override hash arguments given to insert and update statements. This hash is merged into the hash provided to insert or update, so values will override any values given in the insert/update hashes.
DB[:items].set_overrides(:a=>'a', :c=>'c').insert(:a=>'d', :b=>'b')
# INSERT INTO items (a, c, b) VALUES ('a', 'c', 'b')
# File lib/sequel/dataset/query.rb, line 814
814: def set_overrides(hash)
815: clone(:overrides=>hash.merge(@opts[:overrides]||{}))
816: end
Unbind bound variables from this dataset‘s filter and return an array of two objects. The first object is a modified dataset where the filter has been replaced with one that uses bound variable placeholders. The second object is the hash of unbound variables. You can then prepare and execute (or just call) the dataset with the bound variables to get results.
ds, bv = DB[:items].filter(:a=>1).unbind
ds # SELECT * FROM items WHERE (a = $a)
bv # {:a => 1}
ds.call(:select, bv)
# File lib/sequel/dataset/query.rb, line 828
828: def unbind
829: u = Unbinder.new
830: ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join]))
831: [ds, u.binds]
832: end
Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:
| :alias : | Use the given value as the from_self alias |
| :all : | Set to true to use UNION ALL instead of UNION, so duplicate rows can occur |
| :from_self : | Set to false to not wrap the returned dataset in a from_self, use with care. |
DB[:items].union(DB[:other_items]) # SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1 DB[:items].union(DB[:other_items], :all=>true, :from_self=>false) # SELECT * FROM items UNION ALL SELECT * FROM other_items DB[:items].union(DB[:other_items], :alias=>:i) # SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 866
866: def union(dataset, opts={})
867: opts = {:all=>opts} unless opts.is_a?(Hash)
868: compound_clone(:union, dataset, opts)
869: end
Add a condition to the WHERE clause. See filter for argument types.
DB[:items].group(:a).having(:a).filter(:b) # SELECT * FROM items GROUP BY a HAVING a AND b DB[:items].group(:a).having(:a).where(:b) # SELECT * FROM items WHERE b GROUP BY a HAVING a
# File lib/sequel/dataset/query.rb, line 892
892: def where(*cond, &block)
893: _filter(:where, *cond, &block)
894: end
Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query. Options:
| :args : | Specify the arguments/columns for the CTE, should be an array of symbols. |
| :recursive : | Specify that this is a recursive CTE |
DB[:items].with(:items, DB[:syx].filter(:name.like('A%')))
# WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%')) SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 904
904: def with(name, dataset, opts={})
905: raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
906: if hoist_cte?(dataset)
907: s, ds = hoist_cte(dataset)
908: s.with(name, ds, opts)
909: else
910: clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
911: end
912: end
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].select(:i___id, :pi___parent_id).
with_recursive(:t,
DB[:i1].filter(:parent_id=>nil),
DB[:t].join(:t, :i=>:parent_id).select(:i1__id, :i1__parent_id),
:args=>[:i, :pi])
# WITH RECURSIVE t(i, pi) AS (
# SELECT * FROM i1 WHERE (parent_id IS NULL)
# UNION ALL
# SELECT i1.id, i1.parent_id FROM t INNER JOIN t ON (t.i = t.parent_id)
# )
# SELECT i AS id, pi AS parent_id FROM t
# File lib/sequel/dataset/query.rb, line 931
931: def with_recursive(name, nonrecursive, recursive, opts={})
932: raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
933: if hoist_cte?(nonrecursive)
934: s, ds = hoist_cte(nonrecursive)
935: s.with_recursive(name, ds, recursive, opts)
936: elsif hoist_cte?(recursive)
937: s, ds = hoist_cte(recursive)
938: s.with_recursive(name, nonrecursive, ds, opts)
939: else
940: clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
941: end
942: end
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)
# File lib/sequel/dataset/query.rb, line 956
956: def with_sql(sql, *args)
957: if sql.is_a?(Symbol)
958: sql = send(sql, *args)
959: else
960: sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
961: end
962: clone(:sql=>sql)
963: end
Add the dataset to the list of compounds
# File lib/sequel/dataset/query.rb, line 968
968: def compound_clone(type, dataset, opts)
969: if hoist_cte?(dataset)
970: s, ds = hoist_cte(dataset)
971: return s.compound_clone(type, ds, opts)
972: end
973: ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]])
974: opts[:from_self] == false ? ds : ds.from_self(opts)
975: end
Return true if the dataset has a non-nil value for any key in opts.
# File lib/sequel/dataset/query.rb, line 978
978: def options_overlap(opts)
979: !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty?
980: end
Whether this dataset is a simple SELECT * FROM table.
# File lib/sequel/dataset/query.rb, line 983
983: def simple_select_all?
984: o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)}
985: o.length == 1 && (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression))
986: end
These methods don‘t fit cleanly into another section.
| NOTIMPL_MSG | = | "This method must be overridden in Sequel adapters".freeze | ||
| ARRAY_ACCESS_ERROR_MSG | = | 'You cannot call Dataset#[] with an integer or with no arguments.'.freeze | ||
| ARG_BLOCK_ERROR_MSG | = | 'Must use either an argument or a block, not both'.freeze | ||
| IMPORT_ERROR_MSG | = | 'Using Sequel::Dataset#import an empty column array is not allowed'.freeze | ||
| DatasetClass | = | self | ||
| DatasetClass | = | self | ||
| DatasetClass | = | self | ||
| PREPARED_ARG_PLACEHOLDER | = | ':'.freeze | ||
| DatasetClass | = | self | ||
| PREPARED_ARG_PLACEHOLDER | = | LiteralString.new('$').freeze | ||
| DatasetClass | = | self | ||
| DatasetClass | = | self | ||
| JAVA_SQL_TIMESTAMP | = | Java::JavaSQL::Timestamp | Cache Java class constants to speed up lookups | |
| JAVA_SQL_TIME | = | Java::JavaSQL::Time | ||
| JAVA_SQL_DATE | = | Java::JavaSQL::Date | ||
| JAVA_SQL_BLOB | = | Java::JavaSQL::Blob | ||
| JAVA_SQL_CLOB | = | Java::JavaSQL::Clob | ||
| JAVA_BUFFERED_READER | = | Java::JavaIo::BufferedReader | ||
| JAVA_BIG_DECIMAL | = | Java::JavaMath::BigDecimal | ||
| JAVA_BYTE_ARRAY | = | Java::byte[] | ||
| TYPE_TRANSLATOR_INSTANCE | = | tt = TYPE_TRANSLATOR.new | ||
| DECIMAL_METHOD | = | tt.method(:decimal) | Cache type translator methods so that duplicate Method objects are not created. | |
| TIME_METHOD | = | tt.method(:time) | ||
| DATE_METHOD | = | tt.method(:date) | ||
| BUFFERED_READER_METHOD | = | tt.method(:buffered_reader) | ||
| BYTE_ARRAY_METHOD | = | tt.method(:byte_array) | ||
| BLOB_METHOD | = | tt.method(:blob) | ||
| CLOB_METHOD | = | tt.method(:clob) |
| convert_types | [RW] | Whether to convert some Java types to ruby types when retrieving rows. Uses the database‘s setting by default, can be set to false to roughly double performance when fetching rows. |
| db | [RW] | The database related to this dataset. This is the Database instance that will execute all of this dataset‘s queries. |
| opts | [RW] | The hash of options for this dataset, keys are symbols. |
Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:
DB[:posts]
Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.
# File lib/sequel/dataset/misc.rb, line 28
28: def initialize(db, opts = nil)
29: @db = db
30: @opts = opts || {}
31: end
Delete rows matching this dataset
# File lib/sequel/adapters/mysql.rb, line 270
270: def delete
271: execute_dui(delete_sql){|c| return c.affected_rows}
272: end
Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:
DB[:configs].where(:key=>'setting').each_server{|ds| ds.update(:value=>'new_value')}
# File lib/sequel/dataset/misc.rb, line 49
49: def each_server
50: db.servers.each{|s| yield server(s)}
51: end
Yield all rows matching this dataset. If the dataset is set to split multiple statements, yield arrays of hashes one per statement instead of yielding results for all statements as hashes.
# File lib/sequel/adapters/mysql.rb, line 277
277: def fetch_rows(sql, &block)
278: execute(sql) do |r|
279: i = -1
280: cps = db.conversion_procs
281: cols = r.fetch_fields.map do |f|
282: # Pretend tinyint is another integer type if its length is not 1, to
283: # avoid casting to boolean if Sequel::MySQL.convert_tinyint_to_bool
284: # is set.
285: type_proc = f.type == 1 && f.length != 1 ? cps[2] : cps[f.type]
286: [output_identifier(f.name), type_proc, i+=1]
287: end
288: @columns = cols.map{|c| c.first}
289: if opts[:split_multiple_result_sets]
290: s = []
291: yield_rows(r, cols){|h| s << h}
292: yield s
293: else
294: yield_rows(r, cols, &block)
295: end
296: end
297: self
298: end
Yield a hash for each row in the dataset.
# File lib/sequel/adapters/sqlite.rb, line 295
295: def fetch_rows(sql)
296: execute(sql) do |result|
297: i = -1
298: cps = db.conversion_procs
299: type_procs = result.types.map{|t| cps[base_type_name(t)]}
300: cols = result.columns.map{|c| i+=1; [output_identifier(c), i, type_procs[i]]}
301: @columns = cols.map{|c| c.first}
302: result.each do |values|
303: row = {}
304: cols.each do |name,i,type_proc|
305: v = values[i]
306: if type_proc && v.is_a?(String)
307: v = type_proc.call(v)
308: end
309: row[name] = v
310: end
311: yield row
312: end
313: end
314: end
Execute the SQL on the database and yield the rows as hashes with symbol keys.
# File lib/sequel/adapters/do.rb, line 156
156: def fetch_rows(sql)
157: execute(sql) do |reader|
158: cols = @columns = reader.fields.map{|f| output_identifier(f)}
159: while(reader.next!) do
160: h = {}
161: cols.zip(reader.values).each{|k, v| h[k] = v}
162: yield h
163: end
164: end
165: self
166: end
Yield all rows returned by executing the given SQL and converting the types.
# File lib/sequel/adapters/postgres.rb, line 466
466: def fetch_rows(sql, &block)
467: return cursor_fetch_rows(sql, &block) if @opts[:cursor]
468: execute(sql){|res| yield_hash_rows(res, fetch_rows_set_cols(res), &block)}
469: end
Alias of first_source_alias
# File lib/sequel/dataset/misc.rb, line 54
54: def first_source
55: first_source_alias
56: end
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[:table___t].first_source_alias # => :t
# File lib/sequel/dataset/misc.rb, line 66
66: def first_source_alias
67: source = @opts[:from]
68: if source.nil? || source.empty?
69: raise Error, 'No source specified for query'
70: end
71: case s = source.first
72: when SQL::AliasedExpression
73: s.aliaz
74: when Symbol
75: sch, table, aliaz = split_symbol(s)
76: aliaz ? aliaz.to_sym : s
77: else
78: s
79: end
80: end
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[:table___t].first_source_table # => :table
# File lib/sequel/dataset/misc.rb, line 91
91: def first_source_table
92: source = @opts[:from]
93: if source.nil? || source.empty?
94: raise Error, 'No source specified for query'
95: end
96: case s = source.first
97: when SQL::AliasedExpression
98: s.expression
99: when Symbol
100: sch, table, aliaz = split_symbol(s)
101: aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
102: else
103: s
104: end
105: end
Don‘t allow graphing a dataset that splits multiple statements
# File lib/sequel/adapters/mysql.rb, line 301
301: def graph(*)
302: raise(Error, "Can't graph a dataset that splits multiple result sets") if opts[:split_multiple_result_sets]
303: super
304: end
The String instance method to call on identifiers before sending them to the database.
# File lib/sequel/dataset/misc.rb, line 115
115: def identifier_input_method
116: if defined?(@identifier_input_method)
117: @identifier_input_method
118: elsif db.respond_to?(:identifier_input_method)
119: @identifier_input_method = db.identifier_input_method
120: else
121: @identifier_input_method = nil
122: end
123: end
The String instance method to call on identifiers before sending them to the database.
# File lib/sequel/dataset/misc.rb, line 127
127: def identifier_output_method
128: if defined?(@identifier_output_method)
129: @identifier_output_method
130: elsif db.respond_to?(:identifier_output_method)
131: @identifier_output_method = db.identifier_output_method
132: else
133: @identifier_output_method = nil
134: end
135: end
Prepare the given type of query with the given name and store it in the database. Note that a new native prepared statement is created on each call to this prepared statement.
# File lib/sequel/adapters/sqlite.rb, line 319
319: def prepare(type, name=nil, *values)
320: ps = to_prepared_statement(type, values)
321: ps.extend(PreparedStatementMethods)
322: if name
323: ps.prepared_statement_name = name
324: db.prepared_statements[name] = ps
325: end
326: ps
327: end
Prepare the given type of statement with the given name, and store it in the database to be called later.
# File lib/sequel/adapters/postgres.rb, line 593
593: def prepare(type, name=nil, *values)
594: ps = to_prepared_statement(type, values)
595: ps.extend(PreparedStatementMethods)
596: if name
597: ps.prepared_statement_name = name
598: db.prepared_statements[name] = ps
599: end
600: ps
601: end
Create a named prepared statement that is stored in the database (and connection) for reuse.
# File lib/sequel/adapters/jdbc.rb, line 600
600: def prepare(type, name=nil, *values)
601: ps = to_prepared_statement(type, values)
602: ps.extend(PreparedStatementMethods)
603: if name
604: ps.prepared_statement_name = name
605: db.prepared_statements[name] = ps
606: end
607: ps
608: end
PostgreSQL uses $N for placeholders instead of ?, so use a $ as the placeholder.
# File lib/sequel/adapters/postgres.rb, line 607
607: def prepared_arg_placeholder
608: PREPARED_ARG_PLACEHOLDER
609: end
Splits a possible implicit alias in c, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.
# File lib/sequel/dataset/misc.rb, line 154
154: def split_alias(c)
155: case c
156: when Symbol
157: c_table, column, aliaz = split_symbol(c)
158: [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
159: when SQL::AliasedExpression
160: [c.expression, c.aliaz]
161: when SQL::JoinClause
162: [c.table, c.table_alias]
163: else
164: [c, nil]
165: end
166: end
Makes each yield arrays of rows, with each array containing the rows for a given result set. Does not work with graphing. So you can submit SQL with multiple statements and easily determine which statement returned which results.
Modifies the row_proc of the returned dataset so that it still works as expected (running on the hashes instead of on the arrays of hashes). If you modify the row_proc afterward, note that it will receive an array of hashes instead of a hash.
# File lib/sequel/adapters/mysql.rb, line 325
325: def split_multiple_result_sets
326: raise(Error, "Can't split multiple statements on a graphed dataset") if opts[:graph]
327: ds = clone(:split_multiple_result_sets=>true)
328: ds.row_proc = proc{|x| x.map{|h| row_proc.call(h)}} if row_proc
329: ds
330: end
Creates a unique table alias that hasn‘t already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with "_N" if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.
You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.
DB[:table].unused_table_alias(:t) # => :t DB[:table].unused_table_alias(:table) # => :table_0 DB[:table, :table_0].unused_table_alias(:table) # => :table_1 DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2]) # => :table_3
# File lib/sequel/dataset/misc.rb, line 190
190: def unused_table_alias(table_alias, used_aliases = [])
191: table_alias = alias_symbol(table_alias)
192: used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
193: used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
194: if used_aliases.include?(table_alias)
195: i = 0
196: loop do
197: ta = "#{table_alias}_#{i}""#{table_alias}_#{i}"
198: return ta unless used_aliases.include?(ta)
199: i += 1
200: end
201: else
202: table_alias
203: end
204: end
Update the matching rows.
# File lib/sequel/adapters/mysql.rb, line 333
333: def update(values={})
334: execute_dui(update_sql(values)){|c| return c.affected_rows}
335: end
Uses a cursor for fetching records, instead of fetching the entire result set at once. Can be used to process large datasets without holding all rows in memory (which is what the underlying drivers do by default). Options:
Usage:
DB[:huge_table].use_cursor.each{|row| p row}
DB[:huge_table].use_cursor(:rows_per_fetch=>10000).each{|row| p row}
This is untested with the prepared statement/bound variable support, and unlikely to work with either.
# File lib/sequel/adapters/postgres.rb, line 486
486: def use_cursor(opts={})
487: clone(:cursor=>{:rows_per_fetch=>1000}.merge(opts))
488: end
These methods all return booleans, with most describing whether or not the dataset supports a feature.