Class Sequel::Dataset

  1. lib/sequel/dataset.rb
  2. lib/sequel/dataset/convenience.rb
  3. lib/sequel/dataset/prepared_statements.rb
  4. lib/sequel/dataset/sql.rb
  5. lib/sequel/dataset/graph.rb
  6. show all
Parent: Object

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.

Methods added via metaprogramming

Some methods are added via metaprogramming:

  • ! methods - These methods are the same as their non-! counterparts, but they modify the receiver instead of returning a modified copy of the dataset.
  • inner_join, full_outer_join, right_outer_join, left_outer_join - This methods are shortcuts to join_table with the join type already specified.

Included modules

  1. Metaprogramming
  2. Enumerable

Constants

COLUMN_CHANGE_OPTS = [:select, :sql, :from, :join].freeze   The dataset options that require the removal of cached columns if changed.
MUTATION_METHODS = %w'add_graph_aliases and distinct exclude exists filter from from_self full_outer_join graph group group_and_count group_by having inner_join intersect invert join left_outer_join limit naked or order order_by order_more paginate qualify query reject reverse reverse_order right_outer_join select select_all select_more set_defaults set_graph_aliases set_overrides sort sort_by unfiltered ungraphed union unordered where with with_sql'.collect{|x| x.to_sym}   All methods that should have a ! method added that modifies the receiver.
NOTIMPL_MSG = "This method must be overridden in Sequel adapters".freeze
WITH_SUPPORTED = 'with'.freeze
COMMA_SEPARATOR = ', '.freeze
COUNT_OF_ALL_AS_COUNT = SQL::Function.new(:count, LiteralString.new('*'.freeze)).as(:count)
ARRAY_ACCESS_ERROR_MSG = 'You cannot call Dataset#[] with an integer or with no arguments.'.freeze
MAP_ERROR_MSG = 'Using Dataset#map with an argument and a block is not allowed'.freeze
GET_ERROR_MSG = 'must provide argument or block to Dataset#get, not both'.freeze
IMPORT_ERROR_MSG = 'Using Sequel::Dataset#import an empty column array is not allowed'.freeze
PREPARED_ARG_PLACEHOLDER = LiteralString.new('?').freeze
AND_SEPARATOR = " AND ".freeze
BOOL_FALSE = "'f'".freeze
BOOL_TRUE = "'t'".freeze
COLUMN_REF_RE1 = /\A([\w ]+)__([\w ]+)___([\w ]+)\z/.freeze
COLUMN_REF_RE2 = /\A([\w ]+)___([\w ]+)\z/.freeze
COLUMN_REF_RE3 = /\A([\w ]+)__([\w ]+)\z/.freeze
COUNT_FROM_SELF_OPTS = [:distinct, :group, :sql, :limit, :compounds]
DATASET_ALIAS_BASE_NAME = 't'.freeze
INSERT_SQL_BASE = "INSERT INTO ".freeze
IS_LITERALS = {nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze
IS_OPERATORS = ::Sequel::SQL::ComplexExpression::IS_OPERATORS
N_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS
NULL = "NULL".freeze
QUALIFY_KEYS = [:select, :where, :having, :order, :group]
QUESTION_MARK = '?'.freeze
STOCK_COUNT_OPTS = {:select => [SQL::AliasedExpression.new(LiteralString.new("COUNT(*)").freeze, :count)], :order => nil}.freeze
SELECT_CLAUSE_ORDER = %w'with distinct columns from join where group having compounds order limit'.freeze
TWO_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS
WILDCARD = '*'.freeze
SQL_WITH = "WITH ".freeze

External Aliases

inner_join -> join

Attributes

db [RW] The database that corresponds to this dataset
identifier_input_method [RW] Set the method to call on identifiers going into the database for this dataset
identifier_output_method [RW] Set the method to call on identifiers coming the database for this dataset
opts [RW] The hash of options for this dataset, keys are symbols.
quote_identifiers [W] Whether to quote identifiers for this dataset
row_proc [RW] The row_proc for this database, should be a Proc that takes a single hash argument and returns the object you want each to return.

Public class methods

def_mutation_method (*meths)

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.

[show source]
     # File lib/sequel/dataset.rb, line 98
 98:     def self.def_mutation_method(*meths)
 99:       meths.each do |meth|
100:         class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end")
101:       end
102:     end
new (db, opts = nil)

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 adaptor should provide a subclass of Sequel::Dataset, and have the Database#dataset method return an instance of that class.

[show source]
    # File lib/sequel/dataset.rb, line 84
84:     def initialize(db, opts = nil)
85:       @db = db
86:       @quote_identifiers = db.quote_identifiers? if db.respond_to?(:quote_identifiers?)
87:       @identifier_input_method = db.identifier_input_method if db.respond_to?(:identifier_input_method)
88:       @identifier_output_method = db.identifier_output_method if db.respond_to?(:identifier_output_method)
89:       @opts = opts || {}
90:       @row_proc = nil
91:     end

Public instance methods

<< (*args)

Alias for insert, but not aliased directly so subclasses don’t have to override both methods.

[show source]
     # File lib/sequel/dataset.rb, line 108
108:     def <<(*args)
109:       insert(*args)
110:     end
[] (*conditions)

Returns the first record matching the conditions. Examples:

  ds[:id=>1] => {:id=1}
[show source]
    # File lib/sequel/dataset/convenience.rb, line 13
13:     def [](*conditions)
14:       raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
15:       first(*conditions)
16:     end
[]= (conditions, values)

Update all records matching the conditions with the values specified. Examples:

  ds[:id=>1] = {:id=>2} # SQL: UPDATE ... SET id = 2 WHERE id = 1
[show source]
    # File lib/sequel/dataset/convenience.rb, line 22
22:     def []=(conditions, values)
23:       filter(conditions).update(values)
24:     end
add_graph_aliases (graph_aliases)

Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list. See set_graph_aliases.

[show source]
    # File lib/sequel/dataset/graph.rb, line 6
 6:     def add_graph_aliases(graph_aliases)
 7:       ds = select_more(*graph_alias_columns(graph_aliases))
 8:       ds.opts[:graph_aliases] = (ds.opts[:graph_aliases] || ds.opts[:graph][:column_aliases] || {}).merge(graph_aliases)
 9:       ds
10:     end
aliased_expression_sql (ae)

SQL fragment for the aliased expression

[show source]
    # File lib/sequel/dataset/sql.rb, line 35
35:     def aliased_expression_sql(ae)
36:       as_sql(literal(ae.expression), ae.aliaz)
37:     end
all (&block)

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

[show source]
     # File lib/sequel/dataset.rb, line 121
121:     def all(&block)
122:       a = []
123:       each{|r| a << r}
124:       post_load(a)
125:       a.each(&block) if block
126:       a
127:     end
and (*cond, &block)

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.

  ds.filter(:a).and(:b) # SQL: WHERE a AND b
[show source]
    # File lib/sequel/dataset/sql.rb, line 29
29:     def and(*cond, &block)
30:       raise(InvalidOperation, "No existing filter found.") unless @opts[:having] || @opts[:where]
31:       filter(*cond, &block)
32:     end
array_sql (a)

SQL fragment for the SQL array.

[show source]
    # File lib/sequel/dataset/sql.rb, line 40
40:     def array_sql(a)
41:       a.empty? ? '(NULL)' : "(#{expression_list(a)})"     
42:     end
as (aliaz)

Return the dataset as an aliased expression with the given alias. You can use this as a FROM or JOIN dataset, or as a column if this dataset returns a single row and column.

[show source]
     # File lib/sequel/dataset.rb, line 115
115:     def as(aliaz)
116:       ::Sequel::SQL::AliasedExpression.new(self, aliaz)
117:     end
avg (column)

Returns the average value for the given column.

[show source]
    # File lib/sequel/dataset/convenience.rb, line 27
27:     def avg(column)
28:       get{|o| o.avg(column)}
29:     end
call (type, bind_variables={}, values=nil)

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

[show source]
     # File lib/sequel/dataset/prepared_statements.rb, line 176
176:     def call(type, bind_variables={}, values=nil)
177:       prepare(type, nil, values).call(bind_variables)
178:     end
case_expression_sql (ce)

SQL fragment for specifying given CaseExpression.

[show source]
    # File lib/sequel/dataset/sql.rb, line 45
45:     def case_expression_sql(ce)
46:       sql = '(CASE '
47:       sql << "#{literal(ce.expression)} " if ce.expression
48:       ce.conditions.collect{ |c,r|
49:         sql << "WHEN #{literal(c)} THEN #{literal(r)} "
50:       }
51:       sql << "ELSE #{literal(ce.default)} END)"
52:     end
cast_sql (expr, type)

SQL fragment for the SQL CAST expression.

[show source]
    # File lib/sequel/dataset/sql.rb, line 55
55:     def cast_sql(expr, type)
56:       "CAST(#{literal(expr)} AS #{db.cast_type_literal(type)})"
57:     end
clone (opts = {})

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.

[show source]
     # File lib/sequel/dataset.rb, line 132
132:     def clone(opts = {})
133:       c = super()
134:       c.opts = @opts.merge(opts)
135:       c.instance_variable_set(:@columns, nil) if opts.keys.any?{|o| COLUMN_CHANGE_OPTS.include?(o)}
136:       c
137:     end
column_all_sql (ca)

SQL fragment for specifying all columns in a given table.

[show source]
    # File lib/sequel/dataset/sql.rb, line 60
60:     def column_all_sql(ca)
61:       "#{quote_schema_table(ca.table)}.*"
62:     end
columns ()

Returns the columns in the result set in order. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to get a single row. Adapters are expected to fill the columns cache with the column information when a query is performed. If the dataset does not have any rows, this may be an empty array depending on how the adapter is programmed.

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

[show source]
     # File lib/sequel/dataset.rb, line 148
148:     def columns
149:       return @columns if @columns
150:       ds = unfiltered.unordered.clone(:distinct => nil, :limit => 1)
151:       ds.each{break}
152:       @columns = ds.instance_variable_get(:@columns)
153:       @columns || []
154:     end
columns! ()

Remove the cached list of columns and do a SELECT query to find the columns.

[show source]
     # File lib/sequel/dataset.rb, line 158
158:     def columns!
159:       @columns = nil
160:       columns
161:     end
complex_expression_sql (op, args)

SQL fragment for complex expressions

[show source]
    # File lib/sequel/dataset/sql.rb, line 65
65:     def complex_expression_sql(op, args)
66:       case op
67:       when *IS_OPERATORS
68:         r = args.at(1)
69:         if r.nil? || supports_is_true?
70:           raise(InvalidOperation, 'Invalid argument used for IS operator') unless v = IS_LITERALS[r]
71:           "(#{literal(args.at(0))} #{op} #{v})"
72:         elsif op == :IS
73:           complex_expression_sql(:"=", args)
74:         else
75:           complex_expression_sql(:OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)])
76:         end
77:       when *TWO_ARITY_OPERATORS
78:         "(#{literal(args.at(0))} #{op} #{literal(args.at(1))})"
79:       when *N_ARITY_OPERATORS
80:         "(#{args.collect{|a| literal(a)}.join(" #{op} ")})"
81:       when :NOT
82:         "NOT #{literal(args.at(0))}"
83:       when :NOOP
84:         literal(args.at(0))
85:       when :'B~'
86:         "~#{literal(args.at(0))}"
87:       else
88:         raise(InvalidOperation, "invalid operator #{op}")
89:       end
90:     end
count ()

Returns the number of records in the dataset.

[show source]
    # File lib/sequel/dataset/sql.rb, line 93
93:     def count
94:       options_overlap(COUNT_FROM_SELF_OPTS) ? from_self.count : clone(STOCK_COUNT_OPTS).single_value.to_i
95:     end
def_mutation_method (*meths)

Add a mutation method to this dataset instance.

[show source]
     # File lib/sequel/dataset.rb, line 164
164:     def def_mutation_method(*meths)
165:       meths.each do |meth|
166:         instance_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end")
167:       end
168:     end
delete ()

Deletes the records in the dataset. The returned value is generally the number of records deleted, but that is adapter dependent.

[show source]
     # File lib/sequel/dataset.rb, line 172
172:     def delete
173:       execute_dui(delete_sql)
174:     end
delete_sql ()

Formats a DELETE statement using the given options and dataset options.

  dataset.filter{|o| o.price >= 100}.delete_sql #=>
    "DELETE FROM items WHERE (price >= 100)"
[show source]
     # File lib/sequel/dataset/sql.rb, line 101
101:     def delete_sql
102:       opts = @opts
103: 
104:       return static_sql(opts[:sql]) if opts[:sql]
105: 
106:       if opts[:group]
107:         raise InvalidOperation, "Grouped datasets cannot be deleted from"
108:       elsif opts[:from].is_a?(Array) && opts[:from].size > 1
109:         raise InvalidOperation, "Joined datasets cannot be deleted from"
110:       end
111: 
112:       sql = "DELETE FROM #{source_list(opts[:from])}"
113: 
114:       if where = opts[:where]
115:         sql << " WHERE #{literal(where)}"
116:       end
117: 
118:       sql
119:     end
distinct (*args)

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.

 dataset.distinct # SQL: SELECT DISTINCT * FROM items
 dataset.order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
[show source]
     # File lib/sequel/dataset/sql.rb, line 130
130:     def distinct(*args)
131:       raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
132:       clone(:distinct => args)
133:     end
each () {|row_proc.call(r)}| ...}

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

[show source]
     # File lib/sequel/dataset.rb, line 178
178:     def each(&block)
179:       if @opts[:graph]
180:         graph_each(&block)
181:       else
182:         if row_proc = @row_proc
183:           fetch_rows(select_sql){|r| yield row_proc.call(r)}
184:         else
185:           fetch_rows(select_sql, &block)
186:         end
187:       end
188:       self
189:     end
empty? ()

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

[show source]
    # File lib/sequel/dataset/convenience.rb, line 32
32:     def empty?
33:       get(1).nil?
34:     end
except (dataset, opts={})

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

  • :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).sql #=> “SELECT * FROM items EXCEPT SELECT * FROM other_items“

[show source]
     # File lib/sequel/dataset/sql.rb, line 145
145:     def except(dataset, opts={})
146:       opts = {:all=>opts} unless opts.is_a?(Hash)
147:       raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
148:       raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
149:       compound_clone(:except, dataset, opts)
150:     end
exclude (*cond, &block)

Performs the inverse of Dataset#filter.

  dataset.exclude(:category => 'software').sql #=>
    "SELECT * FROM items WHERE (category != 'software')"
[show source]
     # File lib/sequel/dataset/sql.rb, line 156
156:     def exclude(*cond, &block)
157:       clause = (@opts[:having] ? :having : :where)
158:       cond = cond.first if cond.size == 1
159:       cond = filter_expr(cond, &block)
160:       cond = SQL::BooleanExpression.invert(cond)
161:       cond = SQL::BooleanExpression.new(:AND, @opts[clause], cond) if @opts[clause]
162:       clone(clause => cond)
163:     end
exists ()

Returns an EXISTS clause for the dataset as a LiteralString.

  DB.select(1).where(DB[:items].exists).sql
  #=> "SELECT 1 WHERE EXISTS (SELECT * FROM items)"
[show source]
     # File lib/sequel/dataset/sql.rb, line 169
169:     def exists
170:       LiteralString.new("EXISTS (#{select_sql})")
171:     end
fetch_rows (sql, &block)

Executes a select query and fetches records, passing each record to the supplied block. The yielded records should be hashes with symbol keys.

[show source]
     # File lib/sequel/dataset.rb, line 193
193:     def fetch_rows(sql, &block)
194:       raise NotImplementedError, NOTIMPL_MSG
195:     end
filter (*cond, &block)

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:

  • Hash - list of equality/inclusion expressions
  • Array - depends:
    • If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.
    • If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.
  • String - taken literally
  • Symbol - taken as a boolean column argument (e.g. WHERE active)
  • Sequel::SQL::BooleanExpression - an existing condition expression, probably created using the Sequel expression filter DSL.

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.

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

Examples:

  dataset.filter(:id => 3).sql #=>
    "SELECT * FROM items WHERE (id = 3)"
  dataset.filter('price < ?', 100).sql #=>
    "SELECT * FROM items WHERE price < 100"
  dataset.filter([[:id, (1,2,3)], [:id, 0..10]]).sql #=>
    "SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))"
  dataset.filter('price < 100').sql #=>
    "SELECT * FROM items WHERE price < 100"
  dataset.filter(:active).sql #=>
    "SELECT * FROM items WHERE :active
  dataset.filter{|o| o.price < 100}.sql #=>
    "SELECT * FROM items WHERE (price < 100)"

Multiple filter calls can be chained for scoping:

  software = dataset.filter(:category => 'software')
  software.filter{|o| o.price < 100}.sql #=>
    "SELECT * FROM items WHERE ((category = 'software') AND (price < 100))"

See doc/dataset_filters.rdoc for more examples and details.

[show source]
     # File lib/sequel/dataset/sql.rb, line 220
220:     def filter(*cond, &block)
221:       _filter(@opts[:having] ? :having : :where, *cond, &block)
222:     end
first (*args, &block)

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:

  ds.first => {:id=>7}
  ds.first(2) => [{:id=>6}, {:id=>4}]
  ds.order(:id).first(2) => [{:id=>1}, {:id=>2}]
  ds.first(:id=>2) => {:id=>2}
  ds.first("id = 3") => {:id=>3}
  ds.first("id = ?", 4) => {:id=>4}
  ds.first{|o| o.id > 2} => {:id=>5}
  ds.order(:id).first{|o| o.id > 2} => {:id=>3}
  ds.first{|o| o.id > 2} => {:id=>5}
  ds.first("id > ?", 4){|o| o.id < 6} => {:id=>5}
  ds.order(:id).first(2){|o| o.id < 2} => [{:id=>1}]
[show source]
    # File lib/sequel/dataset/convenience.rb, line 55
55:     def first(*args, &block)
56:       ds = block ? filter(&block) : self
57: 
58:       if args.empty?
59:         ds.single_record
60:       else
61:         args = (args.size == 1) ? args.first : args
62:         if Integer === args
63:           ds.limit(args).all
64:         else
65:           ds.filter(args).single_record
66:         end
67:       end
68:     end
first_source ()

Alias for first_source_alias

first_source_alias ()

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 226
226:     def first_source_alias
227:       source = @opts[:from]
228:       if source.nil? || source.empty?
229:         raise Error, 'No source specified for query'
230:       end
231:       case s = source.first
232:       when SQL::AliasedExpression
233:         s.aliaz
234:       when Symbol
235:         sch, table, aliaz = split_symbol(s)
236:         aliaz ? aliaz.to_sym : s
237:       else
238:         s
239:       end
240:     end
from (*source)

Returns a copy of the dataset with the source changed.

  dataset.from # SQL: SELECT *
  dataset.from(:blah) # SQL: SELECT * FROM blah
  dataset.from(:blah, :foo) # SQL: SELECT * FROM blah, foo
[show source]
     # File lib/sequel/dataset/sql.rb, line 248
248:     def from(*source)
249:       table_alias_num = 0
250:       sources = []
251:       source.each do |s|
252:         case s
253:         when Hash
254:           s.each{|k,v| sources << SQL::AliasedExpression.new(k,v)}
255:         when Dataset
256:           sources << SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
257:         when Symbol
258:           sch, table, aliaz = split_symbol(s)
259:           if aliaz
260:             s = sch ? SQL::QualifiedIdentifier.new(sch.to_sym, table.to_sym) : SQL::Identifier.new(table.to_sym)
261:             sources << SQL::AliasedExpression.new(s, aliaz.to_sym)
262:           else
263:             sources << s
264:           end
265:         else
266:           sources << s
267:         end
268:       end
269:       o = {:from=>sources.empty? ? nil : sources}
270:       o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
271:       clone(o)
272:     end
from_self ()

Returns a dataset selecting from the current dataset.

  ds = DB[:items].order(:name)
  ds.sql #=> "SELECT * FROM items ORDER BY name"
  ds.from_self.sql #=> "SELECT * FROM (SELECT * FROM items ORDER BY name)"
[show source]
     # File lib/sequel/dataset/sql.rb, line 279
279:     def from_self
280:       fs = {}
281:       @opts.keys.each{|k| fs[k] = nil} 
282:       clone(fs).from(self)
283:     end
function_sql (f)

SQL fragment specifying an SQL function call

[show source]
     # File lib/sequel/dataset/sql.rb, line 286
286:     def function_sql(f)
287:       args = f.args
288:       "#{f.f}#{args.empty? ? '()' : literal(args)}"
289:     end
get (column=nil, &block)

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

  ds.get(:id)
  ds.get{|o| o.sum(:id)}
[show source]
    # File lib/sequel/dataset/convenience.rb, line 75
75:     def get(column=nil, &block)
76:       if column
77:         raise(Error, GET_ERROR_MSG) if block
78:         select(column).single_value
79:       else
80:         select(&block).single_value
81:       end
82:     end
graph (dataset, join_conditions = nil, options = {}, &block)

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 return a symbol or a dataset
  • join_conditions - Any condition(s) allowed by join_table.
  • options - A hash of graph options. The following options are currently used:
    • :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 join that makes it important to use graph instead of join.
    • :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.
  • block - A block that is passed to join_table.
[show source]
     # File lib/sequel/dataset/graph.rb, line 56
 56:     def graph(dataset, join_conditions = nil, options = {}, &block)
 57:       # Allow the use of a model, dataset, or symbol as the first argument
 58:       # Find the table name/dataset based on the argument
 59:       dataset = dataset.dataset if dataset.respond_to?(:dataset)
 60:       table_alias = options[:table_alias]
 61:       case dataset
 62:       when Symbol
 63:         table = dataset
 64:         dataset = @db[dataset]
 65:         table_alias ||= table
 66:       when ::Sequel::Dataset
 67:         if dataset.simple_select_all?
 68:           table = dataset.opts[:from].first
 69:           table_alias ||= table
 70:         else
 71:           table = dataset
 72:           table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
 73:         end
 74:       else
 75:         raise Error, "The dataset argument should be a symbol, dataset, or model"
 76:       end
 77: 
 78:       # Raise Sequel::Error with explanation that the table alias has been used
 79:       raise_alias_error = lambda do
 80:         raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
 81:           "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
 82:       end
 83: 
 84:       # Only allow table aliases that haven't been used
 85:       raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
 86: 
 87:       # Join the table early in order to avoid cloning the dataset twice
 88:       ds = join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>options[:implicit_qualifier], &block)
 89:       opts = ds.opts
 90: 
 91:       # Whether to include the table in the result set
 92:       add_table = options[:select] == false ? false : true
 93:       # Whether to add the columns to the list of column aliases
 94:       add_columns = !ds.opts.include?(:graph_aliases)
 95: 
 96:       # Setup the initial graph data structure if it doesn't exist
 97:       unless graph = opts[:graph]
 98:         master = ds.first_source_alias
 99:         raise_alias_error.call if master == table_alias
100:         # Master hash storing all .graph related information
101:         graph = opts[:graph] = {}
102:         # Associates column aliases back to tables and columns
103:         column_aliases = graph[:column_aliases] = {}
104:         # Associates table alias (the master is never aliased)
105:         table_aliases = graph[:table_aliases] = {master=>self}
106:         # Keep track of the alias numbers used
107:         ca_num = graph[:column_alias_num] = Hash.new(0)
108:         # All columns in the master table are never
109:         # aliased, but are not included if set_graph_aliases
110:         # has been used.
111:         if add_columns
112:           select = opts[:select] = []
113:           columns.each do |column|
114:             column_aliases[column] = [master, column]
115:             select.push(SQL::QualifiedIdentifier.new(master, column))
116:           end
117:         end
118:       end
119: 
120:       # Add the table alias to the list of aliases
121:       # Even if it isn't been used in the result set,
122:       # we add a key for it with a nil value so we can check if it
123:       # is used more than once
124:       table_aliases = graph[:table_aliases]
125:       table_aliases[table_alias] = add_table ? dataset : nil
126: 
127:       # Add the columns to the selection unless we are ignoring them
128:       if add_table && add_columns
129:         select = opts[:select]
130:         column_aliases = graph[:column_aliases]
131:         ca_num = graph[:column_alias_num]
132:         # Which columns to add to the result set
133:         cols = options[:select] || dataset.columns
134:         # If the column hasn't been used yet, don't alias it.
135:         # If it has been used, try table_column.
136:         # If that has been used, try table_column_N 
137:         # using the next value of N that we know hasn't been
138:         # used
139:         cols.each do |column|
140:           col_alias, identifier = if column_aliases[column]
141:             column_alias = "#{table_alias}_#{column}""#{table_alias}_#{column}"
142:             if column_aliases[column_alias]
143:               column_alias_num = ca_num[column_alias]
144:               column_alias = "#{column_alias}_#{column_alias_num}""#{column_alias}_#{column_alias_num}" 
145:               ca_num[column_alias] += 1
146:             end
147:             [column_alias, SQL::QualifiedIdentifier.new(table_alias, column).as(column_alias)]
148:           else
149:             [column, SQL::QualifiedIdentifier.new(table_alias, column)]
150:           end
151:           column_aliases[col_alias] = [table_alias, column]
152:           select.push(identifier)
153:         end
154:       end
155:       ds
156:     end
grep (cols, terms)

Pattern match any of the columns to any of the terms. The terms can be strings (which use LIKE) or regular expressions (which are only supported in some databases). See Sequel::SQL::StringExpression.like. Note that the total number of pattern matches will be cols.length * terms.length, which could cause performance issues.

  dataset.grep(:a, '%test%') # SQL: SELECT * FROM items WHERE a LIKE '%test%'
  dataset.grep([:a, :b], %w'%test% foo') # SQL: SELECT * FROM items WHERE a LIKE '%test%' OR a LIKE 'foo' OR b LIKE '%test%' OR b LIKE 'foo'
[show source]
     # File lib/sequel/dataset/sql.rb, line 299
299:     def grep(cols, terms)
300:       filter(SQL::BooleanExpression.new(:OR, *Array(cols).collect{|c| SQL::StringExpression.like(c, *terms)}))
301:     end
group (*columns)

Returns a copy of the dataset with the results grouped by the value of the given columns.

  dataset.group(:id) # SELECT * FROM items GROUP BY id
  dataset.group(:id, :name) # SELECT * FROM items GROUP BY id, name
[show source]
     # File lib/sequel/dataset/sql.rb, line 308
308:     def group(*columns)
309:       clone(:group => columns)
310:     end
group_and_count (*columns)

Returns a dataset grouped by the given column with count by group, order by the count of records. Examples:

  ds.group_and_count(:name) => [{:name=>'a', :count=>1}, ...]
  ds.group_and_count(:first_name, :last_name) => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]
[show source]
    # File lib/sequel/dataset/convenience.rb, line 89
89:     def group_and_count(*columns)
90:       group(*columns).select(*(columns + [COUNT_OF_ALL_AS_COUNT])).order(:count)
91:     end
group_by (*columns)

Alias for group

having (*cond, &block)

Returns a copy of the dataset with the HAVING conditions changed. Raises an error if the dataset has not been grouped. See filter for argument types.

  dataset.group(:sum).having(:sum=>10) # SQL: SELECT * FROM items GROUP BY sum HAVING sum = 10
[show source]
     # File lib/sequel/dataset/sql.rb, line 317
317:     def having(*cond, &block)
318:       raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
319:       _filter(:having, *cond, &block)
320:     end
import (columns, values, opts={})

Inserts multiple records into the associated table. This method can be to efficiently insert a large amounts of records into a table. Inserts are automatically wrapped in a transaction.

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

  dataset.import([:x, :y], [[1, 2], [3, 4]])

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

  dataset.import([:x, :y], other_dataset.select(:a___x, :b___y))

The method also accepts a :slice or :commit_every option that specifies the number of records to insert per transaction. This is useful especially when inserting a large number of records, e.g.:

  # this will commit every 50 records
  dataset.import([:x, :y], [[1, 2], [3, 4], ...], :slice => 50)
[show source]
     # File lib/sequel/dataset/convenience.rb, line 111
111:     def import(columns, values, opts={})
112:       return @db.transaction{execute_dui("#{insert_sql_base}#{quote_schema_table(@opts[:from].first)} (#{identifier_list(columns)}) VALUES #{literal(values)}")} if values.is_a?(Dataset)
113: 
114:       return if values.empty?
115:       raise(Error, IMPORT_ERROR_MSG) if columns.empty?
116:       
117:       if slice_size = opts[:commit_every] || opts[:slice]
118:         offset = 0
119:         loop do
120:           @db.transaction(opts){multi_insert_sql(columns, values[offset, slice_size]).each{|st| execute_dui(st)}}
121:           offset += slice_size
122:           break if offset >= values.length
123:         end
124:       else
125:         statements = multi_insert_sql(columns, values)
126:         @db.transaction{statements.each{|st| execute_dui(st)}}
127:       end
128:     end
insert (*values)

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.

[show source]
     # File lib/sequel/dataset.rb, line 199
199:     def insert(*values)
200:       execute_insert(insert_sql(*values))
201:     end
insert_multiple (array, &block)

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 possible faster version that inserts multiple records in one SQL statement.

[show source]
     # File lib/sequel/dataset/sql.rb, line 326
326:     def insert_multiple(array, &block)
327:       if block
328:         array.each {|i| insert(block[i])}
329:       else
330:         array.each {|i| insert(i)}
331:       end
332:     end
insert_sql (*values)

Formats an INSERT statement using the given values. If a hash is given, the resulting statement includes column names. If no values are given, the resulting statement includes a DEFAULT VALUES clause.

  dataset.insert_sql #=> 'INSERT INTO items DEFAULT VALUES'
  dataset.insert_sql(1,2,3) #=> 'INSERT INTO items VALUES (1, 2, 3)'
  dataset.insert_sql(:a => 1, :b => 2) #=>
    'INSERT INTO items (a, b) VALUES (1, 2)'
[show source]
     # File lib/sequel/dataset/sql.rb, line 342
342:     def insert_sql(*values)
343:       return static_sql(@opts[:sql]) if @opts[:sql]
344: 
345:       from = source_list(@opts[:from])
346:       case values.size
347:       when 0
348:         values = {}
349:       when 1
350:         vals = values.at(0)
351:         if [Hash, Dataset, Array].any?{|c| vals.is_a?(c)}
352:           values = vals
353:         elsif vals.respond_to?(:values)
354:           values = vals.values
355:         end
356:       end
357: 
358:       case values
359:       when Array
360:         if values.empty?
361:           insert_default_values_sql
362:         else
363:           "#{insert_sql_base}#{from} VALUES #{literal(values)}#{insert_sql_suffix}"
364:         end
365:       when Hash
366:         values = @opts[:defaults].merge(values) if @opts[:defaults]
367:         values = values.merge(@opts[:overrides]) if @opts[:overrides]
368:         if values.empty?
369:           insert_default_values_sql
370:         else
371:           fl, vl = [], []
372:           values.each do |k, v|
373:             fl << literal(String === k ? k.to_sym : k)
374:             vl << literal(v)
375:           end
376:           "#{insert_sql_base}#{from} (#{fl.join(COMMA_SEPARATOR)}) VALUES (#{vl.join(COMMA_SEPARATOR)})#{insert_sql_suffix}"
377:         end
378:       when Dataset
379:         "#{insert_sql_base}#{from} #{literal(values)}#{insert_sql_suffix}"
380:       end
381:     end
inspect ()

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

[show source]
     # File lib/sequel/dataset.rb, line 205
205:     def inspect
206:       "#<#{self.class}: #{sql.inspect}>"
207:     end
intersect (dataset, opts={})

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

  • :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).sql #=> “SELECT * FROM items INTERSECT SELECT * FROM other_items“

[show source]
     # File lib/sequel/dataset/sql.rb, line 393
393:     def intersect(dataset, opts={})
394:       opts = {:all=>opts} unless opts.is_a?(Hash)
395:       raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
396:       raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
397:       compound_clone(:intersect, dataset, opts)
398:     end
interval (column)

Returns the interval between minimum and maximum values for the given column.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 132
132:     def interval(column)
133:       get{|o| o.max(column) - o.min(column)}
134:     end
invert ()

Inverts the current filter

  dataset.filter(:category => 'software').invert.sql #=>
    "SELECT * FROM items WHERE (category != 'software')"
[show source]
     # File lib/sequel/dataset/sql.rb, line 404
404:     def invert
405:       having, where = @opts[:having], @opts[:where]
406:       raise(Error, "No current filter") unless having || where
407:       o = {}
408:       o[:having] = SQL::BooleanExpression.invert(having) if having
409:       o[:where] = SQL::BooleanExpression.invert(where) if where
410:       clone(o)
411:     end
join_clause_sql (jc)

SQL fragment specifying a JOIN clause without ON or USING.

[show source]
     # File lib/sequel/dataset/sql.rb, line 414
414:     def join_clause_sql(jc)
415:       table = jc.table
416:       table_alias = jc.table_alias
417:       table_alias = nil if table == table_alias
418:       tref = table_ref(table)
419:       " #{join_type_sql(jc.join_type)} #{table_alias ? as_sql(tref, table_alias) : tref}"
420:     end
join_on_clause_sql (jc)

SQL fragment specifying a JOIN clause with ON.

[show source]
     # File lib/sequel/dataset/sql.rb, line 423
423:     def join_on_clause_sql(jc)
424:       "#{join_clause_sql(jc)} ON #{literal(filter_expr(jc.on))}"
425:     end
join_table (type, table, expr=nil, options={}) {|table_name, last_alias, @opts[:join] || []| ...}

Returns a joined dataset. Uses the following arguments:

  • type - The type of join to do (e.g. :inner)
  • table - Depends on type:
    • Dataset - a subselect is performed with an alias of tN for some value of N
    • Model (or anything responding to :table_name) - table.table_name
    • String, Symbol: table
  • expr - specifies conditions, depends on type:
    • Hash, Array with all two pairs - Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.
    • Array - If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.
    • nil - If a block is not given, doesn’t use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses a ON clause based on the block, see below.
    • Everything else - pretty much the same as a using the argument in a call to filter, so strings are considered literal, symbols specify boolean columns, and blockless filter expressions can be used. Uses a JOIN with an ON clause.
  • options - a hash of options, with any of the following keys:
    • :table_alias - the name of the table’s alias when joining, necessary for joining to the same table more than once. No alias is used by default.
    • :implicit_qualifer - The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.
  • block - The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause.
[show source]
     # File lib/sequel/dataset/sql.rb, line 462
462:     def join_table(type, table, expr=nil, options={}, &block)
463:       if [Symbol, String].any?{|c| options.is_a?(c)}
464:         table_alias = options
465:         last_alias = nil 
466:       else
467:         table_alias = options[:table_alias]
468:         last_alias = options[:implicit_qualifier]
469:       end
470:       if Dataset === table
471:         if table_alias.nil?
472:           table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
473:           table_alias = dataset_alias(table_alias_num)
474:         end
475:         table_name = table_alias
476:       else
477:         table = table.table_name if table.respond_to?(:table_name)
478:         table_name = table_alias || table
479:       end
480: 
481:       join = if expr.nil? and !block_given?
482:         SQL::JoinClause.new(type, table, table_alias)
483:       elsif Array === expr and !expr.empty? and expr.all?{|x| Symbol === x}
484:         raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block_given?
485:         SQL::JoinUsingClause.new(expr, type, table, table_alias)
486:       else
487:         last_alias ||= @opts[:last_joined_table] || first_source_alias
488:         if Sequel.condition_specifier?(expr)
489:           expr = expr.collect do |k, v|
490:             k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
491:             v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
492:             [k,v]
493:           end
494:         end
495:         if block_given?
496:           expr2 = yield(table_name, last_alias, @opts[:join] || [])
497:           expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
498:         end
499:         SQL::JoinOnClause.new(expr, type, table, table_alias)
500:       end
501: 
502:       opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name}
503:       opts[:num_dataset_sources] = table_alias_num if table_alias_num
504:       clone(opts)
505:     end
join_using_clause_sql (jc)

SQL fragment specifying a JOIN clause with USING.

[show source]
     # File lib/sequel/dataset/sql.rb, line 428
428:     def join_using_clause_sql(jc)
429:       "#{join_clause_sql(jc)} USING (#{column_list(jc.using)})"
430:     end
last (*args, &block)

Reverses the order and then runs first. 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.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 140
140:     def last(*args, &block)
141:       raise(Error, 'No order specified') unless @opts[:order]
142:       reverse.first(*args, &block)
143:     end
limit (l, o = nil)

If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset.

  dataset.limit(10) # SQL: SELECT * FROM items LIMIT 10
  dataset.limit(10, 20) # SQL: SELECT * FROM items LIMIT 10 OFFSET 20
[show source]
     # File lib/sequel/dataset/sql.rb, line 513
513:     def limit(l, o = nil)
514:       return from_self.limit(l, o) if @opts[:sql]
515: 
516:       if Range === l
517:         o = l.first
518:         l = l.last - l.first + (l.exclude_end? ? 0 : 1)
519:       end
520:       l = l.to_i
521:       raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
522:       opts = {:limit => l}
523:       if o
524:         o = o.to_i
525:         raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
526:         opts[:offset] = o
527:       end
528:       clone(opts)
529:     end
literal (v)

Returns a literal representation of a value to be used as part of an SQL expression.

  dataset.literal("abc'def\\") #=> "'abc''def\\\\'"
  dataset.literal(:items__id) #=> "items.id"
  dataset.literal([1, 2, 3]) => "(1, 2, 3)"
  dataset.literal(DB[:items]) => "(SELECT * FROM items)"
  dataset.literal(:x + 1 > :y) => "((x + 1) > y)"

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 541
541:     def literal(v)
542:       case v
543:       when String
544:         return v if v.is_a?(LiteralString)
545:         v.is_a?(SQL::Blob) ? literal_blob(v) : literal_string(v)
546:       when Symbol
547:         literal_symbol(v)
548:       when Integer
549:         literal_integer(v)
550:       when Hash
551:         literal_hash(v)
552:       when SQL::Expression
553:         literal_expression(v)
554:       when Float
555:         literal_float(v)
556:       when BigDecimal
557:         literal_big_decimal(v)
558:       when NilClass
559:         NULL
560:       when TrueClass
561:         literal_true
562:       when FalseClass
563:         literal_false
564:       when Array
565:         literal_array(v)
566:       when Time
567:         literal_time(v)
568:       when DateTime
569:         literal_datetime(v)
570:       when Date
571:         literal_date(v)
572:       when Dataset
573:         literal_dataset(v)
574:       else
575:         literal_other(v)
576:       end
577:     end
map (column=nil, &block)

Maps column values for each record in the dataset (if a column name is given), or performs the stock mapping functionality of Enumerable. Raises an error if both an argument and block are given. Examples:

  ds.map(:id) => [1, 2, 3, ...]
  ds.map{|r| r[:id] * 2} => [2, 4, 6, ...]
[show source]
     # File lib/sequel/dataset/convenience.rb, line 151
151:     def map(column=nil, &block)
152:       if column
153:         raise(Error, MAP_ERROR_MSG) if block
154:         super(){|r| r[column]}
155:       else
156:         super(&block)
157:       end
158:     end
max (column)

Returns the maximum value for the given column.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 161
161:     def max(column)
162:       get{|o| o.max(column)}
163:     end
min (column)

Returns the minimum value for the given column.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 166
166:     def min(column)
167:       get{|o| o.min(column)}
168:     end
multi_insert (hashes, opts={})

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

  dataset.multi_insert([{:x => 1}, {:x => 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.

You can also use the :slice or :commit_every option that import accepts.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 180
180:     def multi_insert(hashes, opts={})
181:       return if hashes.empty?
182:       columns = hashes.first.keys
183:       import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
184:     end
multi_insert_sql (columns, values)

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

This method should be overridden by descendants if the support inserting multiple records in a single SQL statement.

[show source]
     # File lib/sequel/dataset/sql.rb, line 585
585:     def multi_insert_sql(columns, values)
586:       s = "#{insert_sql_base}#{source_list(@opts[:from])} (#{identifier_list(columns)}) VALUES "
587:       values.map{|r| s + literal(r)}
588:     end
naked ()

Returns a naked dataset clone - i.e. a dataset that returns records as hashes instead of calling the row proc.

[show source]
     # File lib/sequel/dataset.rb, line 211
211:     def naked
212:       ds = clone
213:       ds.row_proc = nil
214:       ds
215:     end
or (*cond, &block)

Adds an alternate filter to an existing filter using OR. If no filter exists an error is raised.

  dataset.filter(:a).or(:b) # SQL: SELECT * FROM items WHERE a OR b
[show source]
     # File lib/sequel/dataset/sql.rb, line 594
594:     def or(*cond, &block)
595:       clause = (@opts[:having] ? :having : :where)
596:       raise(InvalidOperation, "No existing filter found.") unless @opts[clause]
597:       cond = cond.first if cond.size == 1
598:       clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block)))
599:     end
order (*columns, &block)

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

  ds.order(:name).sql #=> 'SELECT * FROM items ORDER BY name'
  ds.order(:a, :b).sql #=> 'SELECT * FROM items ORDER BY a, b'
  ds.order('a + b'.lit).sql #=> 'SELECT * FROM items ORDER BY a + b'
  ds.order(:a + :b).sql #=> 'SELECT * FROM items ORDER BY (a + b)'
  ds.order(:name.desc).sql #=> 'SELECT * FROM items ORDER BY name DESC'
  ds.order(:name.asc).sql #=> 'SELECT * FROM items ORDER BY name ASC'
  ds.order{|o| o.sum(:name)}.sql #=> 'SELECT * FROM items ORDER BY sum(name)'
  ds.order(nil).sql #=> 'SELECT * FROM items'
[show source]
     # File lib/sequel/dataset/sql.rb, line 614
614:     def order(*columns, &block)
615:       columns += Array(virtual_row_block_call(block)) if block
616:       clone(:order => (columns.compact.empty?) ? nil : columns)
617:     end
order_by (*columns, &block)

Alias for order

order_more (*columns, &block)

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

  ds.order(:a).order(:b).sql #=> 'SELECT * FROM items ORDER BY b'
  ds.order(:a).order_more(:b).sql #=> 'SELECT * FROM items ORDER BY a, b'
[show source]
     # File lib/sequel/dataset/sql.rb, line 625
625:     def order_more(*columns, &block)
626:       order(*Array(@opts[:order]).concat(columns), &block)
627:     end
ordered_expression_sql (oe)

SQL fragment for the ordered expression, used in the ORDER BY clause.

[show source]
     # File lib/sequel/dataset/sql.rb, line 631
631:     def ordered_expression_sql(oe)
632:       "#{literal(oe.expression)} #{oe.descending ? 'DESC' : 'ASC'}"
633:     end
placeholder_literal_string_sql (pls)

SQL fragment for a literal string with placeholders

[show source]
     # File lib/sequel/dataset/sql.rb, line 636
636:     def placeholder_literal_string_sql(pls)
637:       args = pls.args.dup
638:       s = pls.str.gsub(QUESTION_MARK){literal(args.shift)}
639:       s = "(#{s})" if pls.parens
640:       s
641:     end
prepare (type, name=nil, values=nil)

Prepare an SQL statement for later execution. This returns a clone of the dataset extended with PreparedStatementMethods, on which you can call call with the hash of bind variables to do substitution. The prepared statement is also stored in the associated database. The following usage is identical:

  ps = prepare(:select, :select_by_name)
  ps.call(:name=>'Blah')
  db.call(:select_by_name, :name=>'Blah')
[show source]
     # File lib/sequel/dataset/prepared_statements.rb, line 189
189:     def prepare(type, name=nil, values=nil)
190:       ps = to_prepared_statement(type, values)
191:       db.prepared_statements[name] = ps if name
192:       ps
193:     end
qualified_identifier_sql (qcr)

SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table).

[show source]
     # File lib/sequel/dataset/sql.rb, line 645
645:     def qualified_identifier_sql(qcr)
646:       [qcr.table, qcr.column].map{|x| [SQL::QualifiedIdentifier, SQL::Identifier, Symbol].any?{|c| x.is_a?(c)} ? literal(x) : quote_identifier(x)}.join('.')
647:     end
qualify (table=first_source)

Qualify to the given table, or first source if not table is given.

[show source]
     # File lib/sequel/dataset/sql.rb, line 650
650:     def qualify(table=first_source)
651:       qualify_to(table)
652:     end
qualify_to (table)

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.

[show source]
     # File lib/sequel/dataset/sql.rb, line 658
658:     def qualify_to(table)
659:       o = @opts
660:       return clone if o[:sql]
661:       h = {}
662:       (o.keys & QUALIFY_KEYS).each do |k|
663:         h[k] = qualified_expression(o[k], table)
664:       end
665:       h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty?
666:       clone(h)
667:     end
qualify_to_first_source ()

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.

[show source]
     # File lib/sequel/dataset/sql.rb, line 674
674:     def qualify_to_first_source
675:       qualify_to(first_source)
676:     end
quote_identifier (name)

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 681
681:     def quote_identifier(name)
682:       return name if name.is_a?(LiteralString)
683:       name = name.value if name.is_a?(SQL::Identifier)
684:       name = input_identifier(name)
685:       name = quoted_identifier(name) if quote_identifiers?
686:       name
687:     end
quote_identifiers? ()

Whether this dataset quotes identifiers.

[show source]
     # File lib/sequel/dataset.rb, line 218
218:     def quote_identifiers?
219:       @quote_identifiers
220:     end
quote_schema_table (table)

Separates the schema from the table and returns a string with them quoted (if quoting identifiers)

[show source]
     # File lib/sequel/dataset/sql.rb, line 691
691:     def quote_schema_table(table)
692:       schema, table = schema_and_table(table)
693:       "#{"#{quote_identifier(schema)}." if schema}#{quote_identifier(table)}"
694:     end
quoted_identifier (name)

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 699
699:     def quoted_identifier(name)
700:       "\"#{name.to_s.gsub('"', '""')}\""
701:     end
range (column)

Returns a Range object made from the minimum and maximum values for the given column.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 188
188:     def range(column)
189:       if r = select{|o| [o.min(column).as(:v1), o.max(column).as(:v2)]}.first
190:         (r[:v1]..r[:v2])
191:       end
192:     end
requires_sql_standard_datetimes? ()

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

[show source]
     # File lib/sequel/dataset.rb, line 224
224:     def requires_sql_standard_datetimes?
225:       false
226:     end
reverse (*order)

Alias for reverse_order

reverse_order (*order)

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 705
705:     def reverse_order(*order)
706:       order(*invert_order(order.empty? ? @opts[:order] : order))
707:     end
schema_and_table (table_name)

Split the schema information from the table

[show source]
     # File lib/sequel/dataset/sql.rb, line 711
711:     def schema_and_table(table_name)
712:       sch = db.default_schema if db
713:       case table_name
714:       when Symbol
715:         s, t, a = split_symbol(table_name)
716:         [s||sch, t]
717:       when SQL::QualifiedIdentifier
718:         [table_name.table, table_name.column]
719:       when SQL::Identifier
720:         [sch, table_name.value]
721:       when String
722:         [sch, table_name]
723:       else
724:         raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
725:       end
726:     end
select (*columns, &block)

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

  dataset.select(:a) # SELECT a FROM items
  dataset.select(:a, :b) # SELECT a, b FROM items
  dataset.select{|o| o.a, o.sum(:b)} # SELECT a, sum(b) FROM items
[show source]
     # File lib/sequel/dataset/sql.rb, line 735
735:     def select(*columns, &block)
736:       columns += Array(virtual_row_block_call(block)) if block
737:       m = []
738:       columns.map do |i|
739:         i.is_a?(Hash) ? m.concat(i.map{|k, v| SQL::AliasedExpression.new(k,v)}) : m << i
740:       end
741:       clone(:select => m)
742:     end
select_all ()

Returns a copy of the dataset selecting the wildcard.

  dataset.select(:a).select_all # SELECT * FROM items
[show source]
     # File lib/sequel/dataset/sql.rb, line 747
747:     def select_all
748:       clone(:select => nil)
749:     end
select_more (*columns, &block)

Returns a copy of the dataset with the given columns added to the existing selected columns.

  dataset.select(:a).select(:b) # SELECT b FROM items
  dataset.select(:a).select_more(:b) # SELECT a, b FROM items
[show source]
     # File lib/sequel/dataset/sql.rb, line 756
756:     def select_more(*columns, &block)
757:       select(*Array(@opts[:select]).concat(columns), &block)
758:     end
select_sql ()

Formats a SELECT statement

  dataset.select_sql # => "SELECT * FROM items"
[show source]
     # File lib/sequel/dataset/sql.rb, line 763
763:     def select_sql
764:       return static_sql(@opts[:sql]) if @opts[:sql]
765:       sql = 'SELECT'
766:       select_clause_order.each{|x| send("select_#{x}_sql""select_#{x}_sql", sql)}
767:       sql
768:     end
server (servr)

Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (which is SELECT uses :read_only database and all other queries use the :default database).

[show source]
     # File lib/sequel/dataset.rb, line 231
231:     def server(servr)
232:       clone(:server=>servr)
233:     end
set (*args)

Alias for set, but not aliased directly so subclasses don’t have to override both methods.

[show source]
     # File lib/sequel/dataset.rb, line 237
237:     def set(*args)
238:       update(*args)
239:     end
set_defaults (hash)

Set the default values for insert and update statements. The values passed to insert or update are merged into this hash.

[show source]
     # File lib/sequel/dataset.rb, line 243
243:     def set_defaults(hash)
244:       clone(:defaults=>(@opts[:defaults]||{}).merge(hash))
245:     end
set_graph_aliases (graph_aliases)

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

  DB[:artists].graph(:albums, :artist_id=>:id).set_graph_aliases(:artist_name=>[:artists, :name], :album_name=>[:albums, :name], :forty_two=>[:albums, :fourtwo, 42]).first
  => {:artists=>{:name=>artists.name}, :albums=>{:name=>albums.name, :fourtwo=>42}}

Arguments:

  • graph_aliases - Should be a hash with keys being symbols of column aliases, and values being arrays with two or three elements. The first element of the array should be the table alias symbol, and the second should be the actual column name symbol. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.
[show source]
     # File lib/sequel/dataset/graph.rb, line 175
175:     def set_graph_aliases(graph_aliases)
176:       ds = select(*graph_alias_columns(graph_aliases))
177:       ds.opts[:graph_aliases] = graph_aliases
178:       ds
179:     end
set_overrides (hash)

Set values that override hash arguments given to insert and update statements. This hash is merged into the hash provided to insert or update.

[show source]
     # File lib/sequel/dataset.rb, line 249
249:     def set_overrides(hash)
250:       clone(:overrides=>hash.merge(@opts[:overrides]||{}))
251:     end
single_record ()

Returns the first record in the dataset.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 195
195:     def single_record
196:       clone(:limit=>1).each{|r| return r}
197:       nil
198:     end
single_value ()

Returns the first value of the first record in the dataset. Returns nil if dataset is empty.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 202
202:     def single_value
203:       if r = naked.clone(:graph=>false).single_record
204:         r.values.first
205:       end
206:     end
sql ()

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 771
771:     def sql
772:       select_sql
773:     end
subscript_sql (s)

SQL fragment for specifying subscripts (SQL arrays)

[show source]
     # File lib/sequel/dataset/sql.rb, line 776
776:     def subscript_sql(s)
777:       "#{literal(s.f)}[#{expression_list(s.sub)}]"
778:     end
sum (column)

Returns the sum for the given column.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 209
209:     def sum(column)
210:       get{|o| o.sum(column)}
211:     end
supports_cte? ()

Whether the dataset supports common table expressions (the WITH clause).

[show source]
     # File lib/sequel/dataset.rb, line 254
254:     def supports_cte?
255:       select_clause_order.include?(WITH_SUPPORTED)
256:     end
supports_distinct_on? ()

Whether the dataset supports the DISTINCT ON clause, true by default.

[show source]
     # File lib/sequel/dataset.rb, line 259
259:     def supports_distinct_on?
260:       true
261:     end
supports_intersect_except? ()

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

[show source]
     # File lib/sequel/dataset.rb, line 264
264:     def supports_intersect_except?
265:       true
266:     end
supports_intersect_except_all? ()

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

[show source]
     # File lib/sequel/dataset.rb, line 269
269:     def supports_intersect_except_all?
270:       true
271:     end
supports_is_true? ()

Whether the dataset supports the IS TRUE syntax.

[show source]
     # File lib/sequel/dataset.rb, line 274
274:     def supports_is_true?
275:       true
276:     end
supports_window_functions? ()

Whether the dataset supports window functions.

[show source]
     # File lib/sequel/dataset.rb, line 279
279:     def supports_window_functions?
280:       false
281:     end
to_csv (include_column_titles = true)

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.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 221
221:     def to_csv(include_column_titles = true)
222:       n = naked
223:       cols = n.columns
224:       csv = ''
225:       csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles
226:       n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"}
227:       csv
228:     end
to_hash (key_column, value_column = nil)

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.

[show source]
     # File lib/sequel/dataset/convenience.rb, line 234
234:     def to_hash(key_column, value_column = nil)
235:       inject({}) do |m, r|
236:         m[r[key_column]] = value_column ? r[value_column] : r
237:         m
238:       end
239:     end
unfiltered ()

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

  dataset.group(:a).having(:a=>1).where(:b).unfiltered # SELECT * FROM items
[show source]
     # File lib/sequel/dataset/sql.rb, line 783
783:     def unfiltered
784:       clone(:where => nil, :having => nil)
785:     end
ungraphed ()

Remove the splitting of results into subhashes. Also removes metadata related to graphing, so you should not call graph any tables to this dataset after calling this method.

[show source]
     # File lib/sequel/dataset/graph.rb, line 184
184:     def ungraphed
185:       clone(:graph=>nil)
186:     end
union (dataset, opts={})

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

  • :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).sql #=> “SELECT * FROM items UNION SELECT * FROM other_items“

[show source]
     # File lib/sequel/dataset/sql.rb, line 796
796:     def union(dataset, opts={})
797:       opts = {:all=>opts} unless opts.is_a?(Hash)
798:       compound_clone(:union, dataset, opts)
799:     end
unordered ()

Returns a copy of the dataset with no order.

  dataset.order(:a).unordered # SELECT * FROM items
[show source]
     # File lib/sequel/dataset/sql.rb, line 804
804:     def unordered
805:       order(nil)
806:     end
update (values={})

Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent.

[show source]
     # File lib/sequel/dataset.rb, line 285
285:     def update(values={})
286:       execute_dui(update_sql(values))
287:     end
update_sql (values = {})

Formats an UPDATE statement using the given values.

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

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 815
815:     def update_sql(values = {})
816:       opts = @opts
817: 
818:       return static_sql(opts[:sql]) if opts[:sql]
819: 
820:       if opts[:group]
821:         raise InvalidOperation, "A grouped dataset cannot be updated"
822:       elsif (opts[:from].size > 1) or opts[:join]
823:         raise InvalidOperation, "A joined dataset cannot be updated"
824:       end
825:       
826:       sql = "UPDATE #{source_list(@opts[:from])} SET "
827:       set = if values.is_a?(Hash)
828:         values = opts[:defaults].merge(values) if opts[:defaults]
829:         values = values.merge(opts[:overrides]) if opts[:overrides]
830:         # get values from hash
831:         values.map do |k, v|
832:           "#{[String, Symbol].any?{|c| k.is_a?(c)} ? quote_identifier(k) : literal(k)} = #{literal(v)}"
833:         end.join(COMMA_SEPARATOR)
834:       else
835:         # copy values verbatim
836:         values
837:       end
838:       sql << set
839:       if where = opts[:where]
840:         sql << " WHERE #{literal(where)}"
841:       end
842: 
843:       sql
844:     end
where (*cond, &block)

Add a condition to the WHERE clause. See filter for argument types.

  dataset.group(:a).having(:a).filter(:b) # SELECT * FROM items GROUP BY a HAVING a AND b
  dataset.group(:a).having(:a).where(:b) # SELECT * FROM items WHERE b GROUP BY a HAVING a
[show source]
     # File lib/sequel/dataset/sql.rb, line 850
850:     def where(*cond, &block)
851:       _filter(:where, *cond, &block)
852:     end
window_function_sql (function, window)

The SQL fragment for the given window function’s function and window.

[show source]
     # File lib/sequel/dataset/sql.rb, line 874
874:     def window_function_sql(function, window)
875:       "#{literal(function)} OVER #{literal(window)}"
876:     end
window_sql (opts)

The SQL fragment for the given window’s options.

[show source]
     # File lib/sequel/dataset/sql.rb, line 855
855:     def window_sql(opts)
856:       raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
857:       window = literal(opts[:window]) if opts[:window]
858:       partition = "PARTITION BY #{expression_list(Array(opts[:partition]))}" if opts[:partition]
859:       order = "ORDER BY #{expression_list(Array(opts[:order]))}" if opts[:order]
860:       frame = case opts[:frame]
861:         when nil
862:           nil
863:         when :all
864:           "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING"
865:         when :rows
866:           "ROWS UNBOUNDED PRECEDING"
867:         else
868:           raise Error, "invalid window frame clause, should be :all, :rows, or nil"
869:       end
870:       "(#{[window, partition, order, frame].compact.join(' ')})"
871:     end
with (name, dataset, opts={})

Add a simple 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
[show source]
     # File lib/sequel/dataset/sql.rb, line 883
883:     def with(name, dataset, opts={})
884:       raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
885:       clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
886:     end
with_recursive (name, nonrecursive, recursive, opts={})

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

  • :args - Specify the arguments/columns for the CTE, should be an array of symbols.
  • :union_all - Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts.
[show source]
     # File lib/sequel/dataset/sql.rb, line 893
893:     def with_recursive(name, nonrecursive, recursive, opts={})
894:       raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
895:       clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
896:     end
with_sql (sql, *args)

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

  dataset.with_sql('SELECT * FROM foo') # SELECT * FROM foo
[show source]
     # File lib/sequel/dataset/sql.rb, line 902
902:     def with_sql(sql, *args)
903:       sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
904:       clone(:sql=>sql)
905:     end

Protected instance methods

compound_from_self ()

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

[show source]
     # File lib/sequel/dataset/sql.rb, line 916
916:     def compound_from_self
917:       (@opts[:limit] || @opts[:order]) ? from_self : self
918:     end
options_overlap (opts)

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

[show source]
     # File lib/sequel/dataset.rb, line 295
295:     def options_overlap(opts)
296:       !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty?
297:     end
simple_select_all? ()

Whether this dataset is a simple SELECT * FROM table.

[show source]
     # File lib/sequel/dataset.rb, line 300
300:     def simple_select_all?
301:       o = @opts.reject{|k,v| v.nil?}
302:       o.length == 1 && (f = o[:from]) && f.length == 1 && f.first.is_a?(Symbol)
303:     end
to_prepared_statement (type, values=nil)

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

[show source]
     # File lib/sequel/dataset/prepared_statements.rb, line 199
199:     def to_prepared_statement(type, values=nil)
200:       ps = clone
201:       ps.extend(PreparedStatementMethods)
202:       ps.prepared_type = type
203:       ps.prepared_modify_values = values
204:       ps
205:     end