class Sequel::DatasetClass

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.

1 - Methods that return modified datasets

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Constants

COLUMN_CHANGE_OPTS

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

CONDITIONED_JOIN_TYPES

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

EXTENSIONS

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

JOIN_METHODS

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

NON_SQL_OPTIONS

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

QUERY_METHODS

Methods that return modified datasets

UNCONDITIONED_JOIN_TYPES

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.

Public Class Methods

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

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

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

# File lib/sequel/dataset/query.rb, line 53
def self.register_extension(ext, mod=nil, &block)
  if mod
    raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block
    if mod.is_a?(Module)
      block = proc{|ds| ds.extend(mod)}
      Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)}
    else
      block = mod
    end
  end
  Sequel.synchronize{EXTENSIONS[ext] = block}
end

Public Instance Methods

and(*cond, &block) click to toggle source

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 71
def and(*cond, &block)
  raise(InvalidOperation, "No existing filter found.") unless @opts[:having] || @opts[:where]
  filter(*cond, &block)
end
clone(opts = {}) click to toggle source

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.

Calls superclass method
# File lib/sequel/dataset/query.rb, line 80
def clone(opts = {})
  c = super()
  c.opts = @opts.merge(opts)
  c.instance_variable_set(:@columns, nil) if opts.keys.any?{|o| COLUMN_CHANGE_OPTS.include?(o)}
  c
end
distinct(*args) click to toggle source

Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. 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 96
def distinct(*args)
  raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
  clone(:distinct => args)
end
except(dataset, opts={}) click to toggle source

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

:alias

Use the given value as the #from_self alias

:all

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

:from_self

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

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

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

DB[:items].except(DB[:other_items], :alias=>:i)
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 118
def except(dataset, opts={})
  opts = {:all=>opts} unless opts.is_a?(Hash)
  raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
  raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
  compound_clone(:except, dataset, opts)
end
exclude(*cond, &block) click to toggle source

Performs the inverse of #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 133
def exclude(*cond, &block)
  _filter_or_exclude(true, @opts[:having] ? :having : :where, *cond, &block)
end
exclude_having(*cond, &block) click to toggle source

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

DB[:items].select_group(:name).exclude_having{count(name) < 2}
# SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)
# File lib/sequel/dataset/query.rb, line 141
def exclude_having(*cond, &block)
  _filter_or_exclude(true, :having, *cond, &block)
end
exclude_where(*cond, &block) click to toggle source

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 155
def exclude_where(*cond, &block)
  _filter_or_exclude(true, :where, *cond, &block)
end
extension(*exts) click to toggle source

Return a clone of the dataset loaded with the extensions, see extension!.

# File lib/sequel/dataset/query.rb, line 160
def extension(*exts)
  clone.extension!(*exts)
end
filter(*cond, &block) click to toggle source

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.

    • Otherwise, treats each argument as a separate condition.

  • 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. 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 216
def filter(*cond, &block)
  _filter(@opts[:having] ? :having : :where, *cond, &block)
end
for_update() click to toggle source

Returns a cloned dataset with a :update lock style.

DB[:table].for_update # SELECT * FROM table FOR UPDATE
# File lib/sequel/dataset/query.rb, line 223
def for_update
  lock_style(:update)
end
from(*source) click to toggle source

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

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 234
def from(*source)
  table_alias_num = 0
  sources = []
  ctes = nil
  source.each do |s|
    case s
    when Hash
      s.each{|k,v| sources << SQL::AliasedExpression.new(k,v)}
    when Dataset
      if hoist_cte?(s)
        ctes ||= []
        ctes += s.opts[:with]
        s = s.clone(:with=>nil)
      end
      sources << SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
    when Symbol
      sch, table, aliaz = split_symbol(s)
      if aliaz
        s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
        sources << SQL::AliasedExpression.new(s, aliaz.to_sym)
      else
        sources << s
      end
    else
      sources << s
    end
  end
  o = {:from=>sources.empty? ? nil : sources}
  o[:with] = (opts[:with] || []) + ctes if ctes
  o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
  clone(o)
end
from_self(opts={}) click to toggle source

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 278
def from_self(opts={})
  fs = {}
  @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)}
  clone(fs).from(opts[:alias] ? as(opts[:alias]) : self)
end
grep(columns, patterns, opts={}) click to toggle source

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions (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 315
def grep(columns, patterns, opts={})
  if opts[:all_patterns]
    conds = Array(patterns).map do |pat|
      SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
    end
    filter(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds))
  else
    conds = Array(columns).map do |c|
      SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
    end
    filter(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds))
  end
end
group(*columns, &block) click to toggle source

Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to 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 336
def group(*columns, &block)
  virtual_row_columns(columns, block)
  clone(:group => (columns.compact.empty? ? nil : columns))
end
group_and_count(*columns, &block) click to toggle source

Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to 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 367
def group_and_count(*columns, &block)
  select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT)
end
group_by(*columns, &block) click to toggle source

Alias of group

# File lib/sequel/dataset/query.rb, line 342
def group_by(*columns, &block)
  group(*columns, &block)
end
group_cube() click to toggle source

Adds the appropriate CUBE syntax to GROUP BY.

# File lib/sequel/dataset/query.rb, line 372
def group_cube
  raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
  clone(:group_options=>:cube)
end
group_rollup() click to toggle source

Adds the appropriate ROLLUP syntax to GROUP BY.

# File lib/sequel/dataset/query.rb, line 378
def group_rollup
  raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
  clone(:group_options=>:rollup)
end
having(*cond, &block) click to toggle source

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 387
def having(*cond, &block)
  _filter(:having, *cond, &block)
end
intersect(dataset, opts={}) click to toggle source

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

:alias

Use the given value as the #from_self alias

:all

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

:from_self

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

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

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

DB[:items].intersect(DB[:other_items], :alias=>:i)
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 408
def intersect(dataset, opts={})
  opts = {:all=>opts} unless opts.is_a?(Hash)
  raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
  raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
  compound_clone(:intersect, dataset, opts)
end
invert() click to toggle source

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 422
def invert
  having, where = @opts[:having], @opts[:where]
  raise(Error, "No current filter") unless having || where
  o = {}
  o[:having] = SQL::BooleanExpression.invert(having) if having
  o[:where] = SQL::BooleanExpression.invert(where) if where
  clone(o)
end
join(*args, &block) click to toggle source

Alias of inner_join

# File lib/sequel/dataset/query.rb, line 432
def join(*args, &block)
  inner_join(*args, &block)
end
join_table(type, table, expr=nil, options={}) { |table_name, last_alias, opts || []| ... } click to toggle source

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

Takes the following arguments:

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

  • table - Depends on type:

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

    • String, Symbol: table

  • expr - specifies conditions, depends on type:

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

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

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

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

    • :qualify - Can be set to false to not do any implicit qualification. Can be set to :deep to use the Qualifier AST Transformer, which will attempt to qualify subexpressions of the expression tree.

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

Examples:

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

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

DB[:a].join_table(:left, :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|
  (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)}
end
# SELECT * FROM a NATURAL JOIN b INNER JOIN c
#   ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
# File lib/sequel/dataset/query.rb, line 489
def join_table(type, table, expr=nil, options={}, &block)
  if hoist_cte?(table)
    s, ds = hoist_cte(table)
    return s.join_table(type, ds, expr, options, &block)
  end

  using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
  if using_join && !supports_join_using?
    h = {}
    expr.each{|e| h[e] = e}
    return join_table(type, table, h, options)
  end

  case options
  when Hash
    table_alias = options[:table_alias]
    last_alias = options[:implicit_qualifier]
    qualify_type = options[:qualify]
  when Symbol, String, SQL::Identifier
    table_alias = options
    last_alias = nil 
  else
    raise Error, "invalid options format for join_table: #{options.inspect}"
  end

  if Dataset === table
    if table_alias.nil?
      table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
      table_alias = dataset_alias(table_alias_num)
    end
    table_name = table_alias
  else
    table, implicit_table_alias = split_alias(table)
    table_alias ||= implicit_table_alias
    table_name = table_alias || table
  end

  join = if expr.nil? and !block
    SQL::JoinClause.new(type, table, table_alias)
  elsif using_join
    raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
    SQL::JoinUsingClause.new(expr, type, table, table_alias)
  else
    last_alias ||= @opts[:last_joined_table] || first_source_alias
    if Sequel.condition_specifier?(expr)
      expr = expr.collect do |k, v|
        case qualify_type
        when false
          nil # Do no qualification
        when :deep
          k = Sequel::Qualifier.new(self, table_name).transform(k)
          v = Sequel::Qualifier.new(self, last_alias).transform(v)
        else
          k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
          v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
        end
        [k,v]
      end
      expr = SQL::BooleanExpression.from_value_pairs(expr)
    end
    if block
      expr2 = yield(table_name, last_alias, @opts[:join] || [])
      expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
    end
    SQL::JoinOnClause.new(expr, type, table, table_alias)
  end

  opts = {:join => (@opts[:join] || []) + [join], :last_joined_table => table_name}
  opts[:num_dataset_sources] = table_alias_num if table_alias_num
  clone(opts)
end
limit(l, o = (no_offset = true; nil)) click to toggle source

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

DB[:items].limit(10) # SELECT * FROM items LIMIT 10
DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20
DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10
DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10
DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
# File lib/sequel/dataset/query.rb, line 578
def limit(l, o = (no_offset = true; nil))
  return from_self.limit(l, o) if @opts[:sql]

  if Range === l
    o = l.first
    l = l.last - l.first + (l.exclude_end? ? 0 : 1)
  end
  l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
  if l.is_a?(Integer)
    raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
  end
  opts = {:limit => l}
  if o
    o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
    if o.is_a?(Integer)
      raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
    end
    opts[:offset] = o
  elsif !no_offset
    opts[:offset] = nil
  end
  clone(opts)
end
lock_style(style) click to toggle source

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

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

DB[:items].lock_style('FOR SHARE NOWAIT') # SELECT * FROM items FOR SHARE NOWAIT
# File lib/sequel/dataset/query.rb, line 611
def lock_style(style)
  clone(:lock => style)
end
naked() click to toggle source

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 621
def naked
  ds = clone
  ds.row_proc = nil
  ds
end
or(*cond, &block) click to toggle source

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 631
def or(*cond, &block)
  clause = (@opts[:having] ? :having : :where)
  raise(InvalidOperation, "No existing filter found.") unless @opts[clause]
  cond = cond.first if cond.size == 1
  clone(clause => SQL::BooleanExpression.new(:OR, @opts[clause], filter_expr(cond, &block)))
end
order(*columns, &block) click to toggle source

Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to 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(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b
DB[:items].order(:a + :b) # SELECT * FROM items ORDER BY (a + b)
DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC
DB[:items].order(Sequel.asc(:name, :nulls=>:last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
DB[:items].order(nil) # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 652
def order(*columns, &block)
  virtual_row_columns(columns, block)
  clone(:order => (columns.compact.empty?) ? nil : columns)
end
order_append(*columns, &block) click to toggle source

Alias of #order_more, for naming consistency with order_prepend.

# File lib/sequel/dataset/query.rb, line 658
def order_append(*columns, &block)
  order_more(*columns, &block)
end
order_by(*columns, &block) click to toggle source

Alias of order

# File lib/sequel/dataset/query.rb, line 663
def order_by(*columns, &block)
  order(*columns, &block)
end
order_more(*columns, &block) click to toggle source

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

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_more(:b) # SELECT * FROM items ORDER BY a, b
# File lib/sequel/dataset/query.rb, line 672
def order_more(*columns, &block)
  columns = @opts[:order] + columns if @opts[:order]
  order(*columns, &block)
end
order_prepend(*columns, &block) click to toggle source

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

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
# File lib/sequel/dataset/query.rb, line 682
def order_prepend(*columns, &block)
  ds = order(*columns, &block)
  @opts[:order] ? ds.order_more(*@opts[:order]) : ds
end
qualify(table=first_source) click to toggle source

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 694
def qualify(table=first_source)
  qualify_to(table)
end
qualify_to(table) click to toggle source

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 705
def qualify_to(table)
  o = @opts
  return clone if o[:sql]
  h = {}
  (o.keys & QUALIFY_KEYS).each do |k|
    h[k] = qualified_expression(o[k], table)
  end
  h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty?
  clone(h)
end
qualify_to_first_source() click to toggle 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.

DB[:items].filter(:id=>1).qualify_to_first_source
# SELECT items.* FROM items WHERE (items.id = 1)
# File lib/sequel/dataset/query.rb, line 724
def qualify_to_first_source
  qualify_to(first_source)
end
returning(*values) click to toggle source

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

DB[:items].returning # RETURNING *
DB[:items].returning(nil) # RETURNING NULL
DB[:items].returning(:id, :name) # RETURNING id, name
# File lib/sequel/dataset/query.rb, line 736
def returning(*values)
  clone(:returning=>values)
end
reverse(*order, &block) click to toggle source

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

DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC
DB[:items].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC
DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
# File lib/sequel/dataset/query.rb, line 747
def reverse(*order, &block)
  virtual_row_columns(order, block)
  order(*invert_order(order.empty? ? @opts[:order] : order))
end
reverse_order(*order, &block) click to toggle source

Alias of reverse

# File lib/sequel/dataset/query.rb, line 753
def reverse_order(*order, &block)
  reverse(*order, &block)
end
select(*columns, &block) click to toggle source

Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to 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 764
def select(*columns, &block)
  virtual_row_columns(columns, block)
  m = []
  columns.each do |i|
    i.is_a?(Hash) ? m.concat(i.map{|k, v| SQL::AliasedExpression.new(k,v)}) : m << i
  end
  clone(:select => m)
end
select_all(*tables) click to toggle source

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

DB[:items].select(:a).select_all # SELECT * FROM items
DB[:items].select_all(:items) # SELECT items.* FROM items
DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
# File lib/sequel/dataset/query.rb, line 780
def select_all(*tables)
  if tables.empty?
    clone(:select => nil)
  else
    select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)})
  end
end
select_append(*columns, &block) click to toggle source

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

DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items
DB[:items].select_append(:b) # SELECT *, b FROM items
# File lib/sequel/dataset/query.rb, line 795
def select_append(*columns, &block)
  cur_sel = @opts[:select]
  if !cur_sel || cur_sel.empty?
    unless supports_select_all_and_column?
      return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block)
    end
    cur_sel = [WILDCARD]
  end
  select(*(cur_sel + columns), &block)
end
select_group(*columns, &block) click to toggle source

Set both the select and group clauses with the given columns. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to 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 815
def select_group(*columns, &block)
  virtual_row_columns(columns, block)
  select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
end
select_more(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected it will 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 827
def select_more(*columns, &block)
  columns = @opts[:select] + columns if @opts[:select]
  select(*columns, &block)
end
server(servr) click to toggle source

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

DB[:items].all # Uses the :read_only or :default server 
DB[:items].delete # Uses the :default server
DB[:items].server(:blah).delete # Uses the :blah server
# File lib/sequel/dataset/query.rb, line 841
def server(servr)
  clone(:server=>servr)
end
set_defaults(hash) click to toggle source

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 851
def set_defaults(hash)
  clone(:defaults=>(@opts[:defaults]||{}).merge(hash))
end
set_overrides(hash) click to toggle source

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 861
def set_overrides(hash)
  clone(:overrides=>hash.merge(@opts[:overrides]||{}))
end
unbind() click to toggle source

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 875
def unbind
  u = Unbinder.new
  ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join]))
  [ds, u.binds]
end
unfiltered() click to toggle source

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

DB[:items].group(:a).having(:a=>1).where(:b).unfiltered
# SELECT * FROM items GROUP BY a
# File lib/sequel/dataset/query.rb, line 885
def unfiltered
  clone(:where => nil, :having => nil)
end
ungrouped() click to toggle source

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

DB[:items].group(:a).having(:a=>1).where(:b).ungrouped
# SELECT * FROM items WHERE b
# File lib/sequel/dataset/query.rb, line 893
def ungrouped
  clone(:group => nil, :having => nil)
end
union(dataset, opts={}) click to toggle source

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

:alias

Use the given value as the #from_self alias

:all

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

:from_self

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

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

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

DB[:items].union(DB[:other_items], :alias=>:i)
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
# File lib/sequel/dataset/query.rb, line 913
def union(dataset, opts={})
  opts = {:all=>opts} unless opts.is_a?(Hash)
  compound_clone(:union, dataset, opts)
end
unlimited() click to toggle source

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

DB[:items].limit(10, 20).unlimited # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 921
def unlimited
  clone(:limit=>nil, :offset=>nil)
end
unordered() click to toggle source

Returns a copy of the dataset with no order.

DB[:items].order(:a).unordered # SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 928
def unordered
  order(nil)
end
where(*cond, &block) click to toggle source

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 939
def where(*cond, &block)
  _filter(:where, *cond, &block)
end
with(name, dataset, opts={}) click to toggle source

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

:args

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

:recursive

Specify that this is a recursive CTE

DB[:items].with(:items, DB[:syx].filter(:name.like('A%')))
# WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%')) SELECT * FROM items
# File lib/sequel/dataset/query.rb, line 951
def with(name, dataset, opts={})
  raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
  if hoist_cte?(dataset)
    s, ds = hoist_cte(dataset)
    s.with(name, ds, opts)
  else
    clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
  end
end
with_recursive(name, nonrecursive, recursive, opts={}) click to toggle source

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

:args

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

:union_all

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

DB[:t].with_recursive(:t,
  DB[:i1].select(:id, :parent_id).filter(:parent_id=>nil),
  DB[:i1].join(:t, :id=>:parent_id).select(:i1__id, :i1__parent_id),
  :args=>[:id, :parent_id])

# WITH RECURSIVE "t"("id", "parent_id") AS (
#   SELECT "id", "parent_id" FROM "i1" WHERE ("parent_id" IS NULL)
#   UNION ALL
#   SELECT "i1"."id", "i1"."parent_id" FROM "i1" INNER JOIN "t" ON ("t"."id" = "i1"."parent_id")
# ) SELECT * FROM "t"
# File lib/sequel/dataset/query.rb, line 977
def with_recursive(name, nonrecursive, recursive, opts={})
  raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
  if hoist_cte?(nonrecursive)
    s, ds = hoist_cte(nonrecursive)
    s.with_recursive(name, ds, recursive, opts)
  elsif hoist_cte?(recursive)
    s, ds = hoist_cte(recursive)
    s.with_recursive(name, nonrecursive, ds, opts)
  else
    clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
  end
end
with_sql(sql, *args) click to toggle source

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

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

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

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

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

DB[:items].with_sql(:insert_sql, :b=>1) # INSERT INTO items (b) VALUES (1)
# File lib/sequel/dataset/query.rb, line 1002
def with_sql(sql, *args)
  if sql.is_a?(Symbol)
    sql = send(sql, *args)
  else
    sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
  end
  clone(:sql=>sql)
end

Protected Instance Methods

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

Add the dataset to the list of compounds

# File lib/sequel/dataset/query.rb, line 1014
def compound_clone(type, dataset, opts)
  if hoist_cte?(dataset)
    s, ds = hoist_cte(dataset)
    return s.compound_clone(type, ds, opts)
  end
  ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]])
  opts[:from_self] == false ? ds : ds.from_self(opts)
end
options_overlap(opts) click to toggle source

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

# File lib/sequel/dataset/query.rb, line 1024
def options_overlap(opts)
  !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty?
end
simple_select_all?() click to toggle source

Whether this dataset is a simple SELECT * FROM table.

# File lib/sequel/dataset/query.rb, line 1029
def simple_select_all?
  o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)}
  o.length == 1 && (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression))
end

Private Instance Methods

_filter(clause, *cond, &block) click to toggle source

Internal filter method so it works on either the having or where clauses.

# File lib/sequel/dataset/query.rb, line 1050
def _filter(clause, *cond, &block)
  _filter_or_exclude(false, clause, *cond, &block)
end
_filter_or_exclude(invert, clause, *cond, &block) click to toggle source

Internal filter/exclude method so it works on either the having or where clauses.

# File lib/sequel/dataset/query.rb, line 1037
def _filter_or_exclude(invert, clause, *cond, &block)
  cond = cond.first if cond.size == 1
  if cond.respond_to?(:empty?) && cond.empty? && !block
    clone
  else
    cond = filter_expr(cond, &block)
    cond = SQL::BooleanExpression.invert(cond) if invert
    cond = SQL::BooleanExpression.new(:AND, @opts[clause], cond) if @opts[clause]
    clone(clause => cond)
  end
end
default_server() click to toggle source

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

# File lib/sequel/dataset/query.rb, line 1125
def default_server
  @opts[:server] ? self : clone(:server=>:default)
end
filter_expr(expr = nil, &block) click to toggle source

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

# File lib/sequel/dataset/query.rb, line 1055
def filter_expr(expr = nil, &block)
  expr = nil if expr == []
  if expr && block
    return SQL::BooleanExpression.new(:AND, filter_expr(expr), filter_expr(block))
  elsif block
    expr = block
  end
  case expr
  when Hash
    SQL::BooleanExpression.from_value_pairs(expr)
  when Array
    if (sexpr = expr.at(0)).is_a?(String)
      SQL::PlaceholderLiteralString.new(sexpr, expr[1..-1], true)
    elsif Sequel.condition_specifier?(expr)
      SQL::BooleanExpression.from_value_pairs(expr)
    else
      SQL::BooleanExpression.new(:AND, *expr.map{|x| filter_expr(x)})
    end
  when Proc
    filter_expr(Sequel.virtual_row(&expr))
  when SQL::NumericExpression, SQL::StringExpression
    raise(Error, "Invalid SQL Expression type: #{expr.inspect}") 
  when Symbol, SQL::Expression
    expr
  when TrueClass, FalseClass
    if supports_where_true?
      SQL::BooleanExpression.new(:NOOP, expr)
    elsif expr
      SQL::Constants::SQLTRUE
    else
      SQL::Constants::SQLFALSE
    end
  when String
    LiteralString.new("(#{expr})")
  else
    raise(Error, "Invalid filter argument: #{expr.inspect}")
  end
end
hoist_cte(ds) click to toggle source

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

# File lib/sequel/dataset/query.rb, line 1097
def hoist_cte(ds)
  [clone(:with => (opts[:with] || []) + ds.opts[:with]), ds.clone(:with => nil)]
end
hoist_cte?(ds) click to toggle source

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

# File lib/sequel/dataset/query.rb, line 1102
def hoist_cte?(ds)
  ds.is_a?(Dataset) && ds.opts[:with] && !supports_cte_in_subqueries?
end
invert_order(order) click to toggle source

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

DB[:items].invert_order([Sequel.desc(:id)]]) #=> [Sequel.asc(:id)]
DB[:items].invert_order([:category, Sequel.desc(:price)]) #=> [Sequel.desc(:category), Sequel.asc(:price)]
# File lib/sequel/dataset/query.rb, line 1111
def invert_order(order)
  return nil unless order
  order.map do |f|
    case f
    when SQL::OrderedExpression
      f.invert
    else
      SQL::OrderedExpression.new(f)
    end
  end
end
virtual_row_columns(columns, block) click to toggle source

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

# File lib/sequel/dataset/query.rb, line 1131
def virtual_row_columns(columns, block)
  columns.concat(Array(Sequel.virtual_row(&block))) if block
end

2 - Methods that execute code on the database

↑ top

Constants

ACTION_METHODS

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

Public Instance Methods

<<(arg) click to toggle source

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

DB[:items] << {:id=>0, :name=>'Zero'} << DB[:old_items].select(:id, name)
# File lib/sequel/dataset/actions.rb, line 22
def <<(arg)
  insert(arg)
  self
end
[](*conditions) click to toggle source

Returns the first record matching the conditions. Examples:

DB[:table][:id=>1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=1}
# File lib/sequel/dataset/actions.rb, line 31
def [](*conditions)
  raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
  first(*conditions)
end
[]=(conditions, values) click to toggle source

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 41
def []=(conditions, values)
  filter(conditions).update(values)
end
all(&block) click to toggle source

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

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

# Iterate over all rows in the table
DB[:table].all{|row| p row}
# File lib/sequel/dataset/actions.rb, line 53
def all(&block)
  a = []
  each{|r| a << r}
  post_load(a)
  a.each(&block) if block
  a
end
avg(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1
# => 3
DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1
# => 1
# File lib/sequel/dataset/actions.rb, line 68
def avg(column=Sequel.virtual_row(&Proc.new))
  aggregate_dataset.get{avg(column)}
end
columns() click to toggle source

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

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

DB[:table].columns
# => [:id, :name]
# File lib/sequel/dataset/actions.rb, line 81
def columns
  return @columns if @columns
  ds = unfiltered.unordered.naked.clone(:distinct => nil, :limit => 1, :offset=>nil)
  ds.each{break}
  @columns = ds.instance_variable_get(:@columns)
  @columns || []
end
columns!() click to toggle source

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

DB[:table].columns!
# => [:id, :name]
# File lib/sequel/dataset/actions.rb, line 94
def columns!
  @columns = nil
  columns
end
count(arg=(no_arg=true), &block) click to toggle source

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

DB[:table].count # SELECT COUNT(*) AS count FROM table LIMIT 1
# => 3
DB[:table].count(:column) # SELECT COUNT(column) AS count FROM table LIMIT 1
# => 2
DB[:table].count{foo(column)} # SELECT COUNT(foo(column)) AS count FROM table LIMIT 1
# => 1
# File lib/sequel/dataset/actions.rb, line 110
def count(arg=(no_arg=true), &block)
  if no_arg
    if block
      arg = Sequel.virtual_row(&block)
      aggregate_dataset.get{COUNT(arg).as(count)}
    else
      aggregate_dataset.get{COUNT(:*){}.as(count)}.to_i
    end
  elsif block
    raise Error, 'cannot provide both argument and block to Dataset#count'
  else
    aggregate_dataset.get{COUNT(arg).as(count)}
  end
end
delete(&block) click to toggle source

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 130
def delete(&block)
  sql = delete_sql
  if uses_returning?(:delete)
    returning_fetch_rows(sql, &block)
  else
    execute_dui(sql)
  end
end
each() { |r| ... } click to toggle source

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

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

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

# File lib/sequel/dataset/actions.rb, line 148
def each
  if @opts[:graph]
    graph_each{|r| yield r}
  elsif defined?(@row_proc) && (row_proc = @row_proc)
    fetch_rows(select_sql){|r| yield row_proc.call(r)}
  else
    fetch_rows(select_sql){|r| yield r}
  end
  self
end
empty?() click to toggle source

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

DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
# => false
# File lib/sequel/dataset/actions.rb, line 163
def empty?
  get(Sequel::SQL::AliasedExpression.new(1, :one)).nil?
end
fetch_rows(sql) click to toggle source

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 171
def fetch_rows(sql)
  raise NotImplemented, NOTIMPL_MSG
end
first(*args, &block) click to toggle source

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.

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

Examples:

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

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

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

DB[:table].first("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 210
def first(*args, &block)
  ds = block ? filter(&block) : self

  if args.empty?
    ds.single_record
  else
    args = (args.size == 1) ? args.first : args
    if Integer === args
      ds.limit(args).all
    else
      ds.filter(args).single_record
    end
  end
end
first!(*args, &block) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 227
def first!(*args, &block)
  first(*args, &block) || raise(Sequel::NoMatchingRow)
end
get(column=(no_arg=true; nil), &block) click to toggle source

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

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

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

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

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

DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1
# => [6, 'foo']
# File lib/sequel/dataset/actions.rb, line 249
def get(column=(no_arg=true; nil), &block)
  ds = naked
  if block
    raise(Error, ARG_BLOCK_ERROR_MSG) unless no_arg
    ds = ds.select(&block)
    column = ds.opts[:select]
    column = nil if column.is_a?(Array) && column.length < 2
  else
    ds = if column.is_a?(Array)
      ds.select(*column)
    else
      ds.select(column)
    end
  end

  if column.is_a?(Array)
   if r = ds.single_record
     r.values_at(*column.map{|c| hash_key_symbol(c)})
   end
  else
    ds.single_value
  end
end
import(columns, values, opts={}) click to toggle source

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

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

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

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

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

Options:

:commit_every

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

: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 296
def import(columns, values, opts={})
  return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)

  return if values.empty?
  raise(Error, IMPORT_ERROR_MSG) if columns.empty?
  ds = opts[:server] ? server(opts[:server]) : self
  
  if slice_size = opts[:commit_every] || opts[:slice]
    offset = 0
    rows = []
    while offset < values.length
      rows << ds._import(columns, values[offset, slice_size], opts)
      offset += slice_size
    end
    rows.flatten
  else
    ds._import(columns, values, opts)
  end
end
insert(*values, &block) click to toggle source

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 351
def insert(*values, &block)
  sql = insert_sql(*values)
  if uses_returning?(:insert)
    returning_fetch_rows(sql, &block)
  else
    execute_insert(sql)
  end
end
insert_multiple(array, &block) click to toggle source

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; row }
# => [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 375
def insert_multiple(array, &block)
  if block
    array.map{|i| insert(block.call(i))}
  else
    array.map{|i| insert(i)}
  end
end
interval(column=Sequel.virtual_row(&Proc.new)) click to toggle source

Returns the interval between minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].interval(:id) # SELECT (max(id) - min(id)) FROM table LIMIT 1
# => 6
DB[:table].interval{function(column)} # SELECT (max(function(column)) - min(function(column))) FROM table LIMIT 1
# => 7
# File lib/sequel/dataset/actions.rb, line 390
def interval(column=Sequel.virtual_row(&Proc.new))
  aggregate_dataset.get{max(column) - min(column)}
end
last(*args, &block) click to toggle source

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

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

DB[:table].order(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
# => [{:id=>1}, {:id=>2}]
# File lib/sequel/dataset/actions.rb, line 404
def last(*args, &block)
  raise(Error, 'No order specified') unless @opts[:order]
  reverse.first(*args, &block)
end
map(column=nil, &block) click to toggle source

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'], ...]
Calls superclass method
# File lib/sequel/dataset/actions.rb, line 423
def map(column=nil, &block)
  if column
    raise(Error, ARG_BLOCK_ERROR_MSG) if block
    return naked.map(column) if row_proc
    if column.is_a?(Array)
      super(){|r| r.values_at(*column)}
    else
      super(){|r| r[column]}
    end
  else
    super(&block)
  end
end
max(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
# => 10
DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1
# => 7
# File lib/sequel/dataset/actions.rb, line 444
def max(column=Sequel.virtual_row(&Proc.new))
  aggregate_dataset.get{max(column)}
end
min(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1
# => 1
DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1
# => 0
# File lib/sequel/dataset/actions.rb, line 455
def min(column=Sequel.virtual_row(&Proc.new))
  aggregate_dataset.get{min(column)}
end
multi_insert(hashes, opts={}) click to toggle source

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

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

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

This respects the same options as import.

# File lib/sequel/dataset/actions.rb, line 471
def multi_insert(hashes, opts={})
  return if hashes.empty?
  columns = hashes.first.keys
  import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
end
paged_each(opts={}) { |row| ... } click to toggle source

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

Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to make sure that all rows in the dataset are yielded and none are yielded twice, the dataset must have an unambiguous order. Sequel requires that datasets using this method have an order, but it cannot ensure that the order is unambiguous.

Options:

:rows_per_fetch

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

# File lib/sequel/dataset/actions.rb, line 490
def paged_each(opts={})
  unless @opts[:order]
    raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
  end

  total_limit = @opts[:limit]
  offset = @opts[:offset] || 0

  if server = @opts[:server]
    opts = opts.merge(:server=>server)
  end

  rows_per_fetch = opts[:rows_per_fetch] || 1000
  num_rows_yielded = rows_per_fetch
  total_rows = 0

  db.transaction(opts) do
    while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
      if total_limit && total_rows + rows_per_fetch > total_limit
        rows_per_fetch = total_limit - total_rows
      end

      num_rows_yielded = 0
      limit(rows_per_fetch, offset).each do |row|
        num_rows_yielded += 1
        total_rows += 1 if total_limit
        yield row
      end

      offset += rows_per_fetch
    end
  end

  self
end
range(column=Sequel.virtual_row(&Proc.new)) click to toggle source

Returns a Range instance made from the minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1
# => 1..10
DB[:table].interval{function(column)} # SELECT max(function(column)) AS v1, min(function(column)) AS v2 FROM table LIMIT 1
# => 0..7
# File lib/sequel/dataset/actions.rb, line 533
def range(column=Sequel.virtual_row(&Proc.new))
  if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first
    (r[:v1]..r[:v2])
  end
end
select_hash(key_column, value_column) click to toggle source

Returns a hash with key_column values as keys and value_column values as values. Similar to #to_hash, but only selects the columns given.

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

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

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

When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

# File lib/sequel/dataset/actions.rb, line 554
def select_hash(key_column, value_column)
  _select_hash(:to_hash, key_column, value_column)
end
select_hash_groups(key_column, value_column) click to toggle source

Returns a hash with key_column values as keys and an array of value_column values. Similar to #to_hash_groups, but only selects the columns given.

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

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

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

When using this method, you must be sure that each expression has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

# File lib/sequel/dataset/actions.rb, line 573
def select_hash_groups(key_column, value_column)
  _select_hash(:to_hash_groups, key_column, value_column)
end
select_map(column=nil, &block) click to toggle source

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

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

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

You can also provide an array of column names:

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

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

# File lib/sequel/dataset/actions.rb, line 597
def select_map(column=nil, &block)
  _select_map(column, false, &block)
end
select_order_map(column=nil, &block) click to toggle source

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

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

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

You can also provide an array of column names:

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

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine. Usually you can do this by calling the as method on the expression and providing an alias.

# File lib/sequel/dataset/actions.rb, line 617
def select_order_map(column=nil, &block)
  _select_map(column, true, &block)
end
set(*args) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 623
def set(*args)
  update(*args)
end
single_record() click to toggle source

Returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method.

# File lib/sequel/dataset/actions.rb, line 630
def single_record
  clone(:limit=>1).each{|r| return r}
  nil
end
single_value() click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 638
def single_value
  if r = naked.ungraphed.single_record
    r.values.first
  end
end
sum(column=Sequel.virtual_row(&Proc.new)) click to toggle source

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

DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
# => 55
DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1
# => 10
# File lib/sequel/dataset/actions.rb, line 651
def sum(column=Sequel.virtual_row(&Proc.new))
  aggregate_dataset.get{sum(column)}
end
to_csv(include_column_titles = true) click to toggle source

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 668
def to_csv(include_column_titles = true)
  n = naked
  cols = n.columns
  csv = ''
  csv << "#{cols.join(COMMA_SEPARATOR)}\r\n" if include_column_titles
  n.each{|r| csv << "#{cols.collect{|c| r[c]}.join(COMMA_SEPARATOR)}\r\n"}
  csv
end
to_hash(key_column, value_column = nil) click to toggle source

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

DB[:table].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 696
def to_hash(key_column, value_column = nil)
  h = {}
  if value_column
    return naked.to_hash(key_column, value_column) if row_proc
    if value_column.is_a?(Array)
      if key_column.is_a?(Array)
        each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
      else
        each{|r| h[r[key_column]] = r.values_at(*value_column)}
      end
    else
      if key_column.is_a?(Array)
        each{|r| h[r.values_at(*key_column)] = r[value_column]}
      else
        each{|r| h[r[key_column]] = r[value_column]}
      end
    end
  elsif key_column.is_a?(Array)
    each{|r| h[r.values_at(*key_column)] = r}
  else
    each{|r| h[r[key_column]] = r}
  end
  h
end
to_hash_groups(key_column, value_column = nil) click to toggle source

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

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

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

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

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

DB[:table].to_hash([:first, :middle]) # SELECT * FROM table
# {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}
# File lib/sequel/dataset/actions.rb, line 739
def to_hash_groups(key_column, value_column = nil)
  h = {}
  if value_column
    return naked.to_hash_groups(key_column, value_column) if row_proc
    if value_column.is_a?(Array)
      if key_column.is_a?(Array)
        each{|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
      else
        each{|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
      end
    else
      if key_column.is_a?(Array)
        each{|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
      else
        each{|r| (h[r[key_column]] ||= []) << r[value_column]}
      end
    end
  elsif key_column.is_a?(Array)
    each{|r| (h[r.values_at(*key_column)] ||= []) << r}
  else
    each{|r| (h[r[key_column]] ||= []) << r}
  end
  h
end
truncate() click to toggle source

Truncates the dataset. Returns nil.

DB[:table].truncate # TRUNCATE table
# => nil
# File lib/sequel/dataset/actions.rb, line 768
def truncate
  execute_ddl(truncate_sql)
end
update(values={}, &block) click to toggle source

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 782
def update(values={}, &block)
  sql = update_sql(values)
  if uses_returning?(:update)
    returning_fetch_rows(sql, &block)
  else
    execute_dui(sql)
  end
end
with_sql_delete(sql) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 794
def with_sql_delete(sql)
  execute_dui(sql)
end

Protected Instance Methods

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

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

# File lib/sequel/dataset/actions.rb, line 803
def _import(columns, values, opts)
  trans_opts = opts.merge(:server=>@opts[:server])
  if opts[:return] == :primary_key
    @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
  else
    stmts = multi_insert_sql(columns, values)
    @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
  end
end
_select_map_multiple(ret_cols) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 814
def _select_map_multiple(ret_cols)
  map{|r| r.values_at(*ret_cols)}
end
_select_map_single() click to toggle source

Returns an array of the first value in each row.

# File lib/sequel/dataset/actions.rb, line 819
def _select_map_single
  map{|r| r.values.first}
end

Private Instance Methods

_select_hash(meth, key_column, value_column) click to toggle source

Internals of select_hash and select_hash_groups

# File lib/sequel/dataset/actions.rb, line 826
def _select_hash(meth, key_column, value_column)
  if key_column.is_a?(Array)
    if value_column.is_a?(Array)
      select(*(key_column + value_column)).send(meth, key_column.map{|c| hash_key_symbol(c)}, value_column.map{|c| hash_key_symbol(c)})
    else
      select(*(key_column + [value_column])).send(meth, key_column.map{|c| hash_key_symbol(c)}, hash_key_symbol(value_column))
    end
  elsif value_column.is_a?(Array)
    select(key_column, *value_column).send(meth, hash_key_symbol(key_column), value_column.map{|c| hash_key_symbol(c)})
  else
    select(key_column, value_column).send(meth, hash_key_symbol(key_column), hash_key_symbol(value_column))
  end
end
_select_map(column, order, &block) click to toggle source

Internals of select_map and select_order_map

# File lib/sequel/dataset/actions.rb, line 841
def _select_map(column, order, &block)
  ds = naked.ungraphed
  columns = Array(column)
  virtual_row_columns(columns, block)
  select_cols = order ? columns.map{|c| c.is_a?(SQL::OrderedExpression) ? c.expression : c} : columns
  ds = ds.select(*select_cols)
  ds = ds.order(*columns.map{|c| unaliased_identifier(c)}) if order
  if column.is_a?(Array) || (columns.length > 1)
    ds._select_map_multiple(select_cols.map{|c| hash_key_symbol(c)})
  else
    ds._select_map_single
  end
end
default_server_opts(opts) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 856
def default_server_opts(opts)
  {:server=>@opts[:server] || :default}.merge(opts)
end
execute(sql, opts={}, &block) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 862
def execute(sql, opts={}, &block)
  @db.execute(sql, {:server=>@opts[:server] || :read_only}.merge(opts), &block)
end
execute_ddl(sql, opts={}, &block) click to toggle source

Execute the given SQL on the database using execute_ddl.

# File lib/sequel/dataset/actions.rb, line 867
def execute_ddl(sql, opts={}, &block)
  @db.execute_ddl(sql, default_server_opts(opts), &block)
  nil
end
execute_dui(sql, opts={}, &block) click to toggle source

Execute the given SQL on the database using execute_dui.

# File lib/sequel/dataset/actions.rb, line 873
def execute_dui(sql, opts={}, &block)
  @db.execute_dui(sql, default_server_opts(opts), &block)
end
execute_insert(sql, opts={}, &block) click to toggle source

Execute the given SQL on the database using execute_insert.

# File lib/sequel/dataset/actions.rb, line 878
def execute_insert(sql, opts={}, &block)
  @db.execute_insert(sql, default_server_opts(opts), &block)
end
hash_key_symbol(s, recursing=false) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned.

# File lib/sequel/dataset/actions.rb, line 885
def hash_key_symbol(s, recursing=false)
  case s
  when Symbol
    _, c, a = split_symbol(s)
    (a || c).to_sym
  when SQL::Identifier, SQL::Wrapper
    hash_key_symbol(s.value, true)
  when SQL::QualifiedIdentifier
    hash_key_symbol(s.column, true)
  when SQL::AliasedExpression
    hash_key_symbol(s.aliaz, true)
  when String
    if recursing
      s.to_sym
    else
      raise(Error, "#{s.inspect} is not supported, should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression") 
    end
  else
    raise(Error, "#{s.inspect} is not supported, should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression") 
  end
end
output_identifier(v) click to toggle source

Modify the identifier returned from the database based on the identifier_output_method.

# File lib/sequel/dataset/actions.rb, line 909
def output_identifier(v)
  v = 'untitled' if v == ''
  (i = identifier_output_method) ? v.to_s.send(i).to_sym : v.to_sym
end
post_load(all_records) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 918
def post_load(all_records)
end
returning_fetch_rows(sql, &block) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 924
def returning_fetch_rows(sql, &block)
  if block
    default_server.fetch_rows(sql, &block)
    nil
  else
    rows = []
    default_server.fetch_rows(sql){|r| rows << r}
    rows
  end
end
unaliased_identifier(c) click to toggle source

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

# File lib/sequel/dataset/actions.rb, line 938
def unaliased_identifier(c)
  case c
  when Symbol
    c_table, column, _ = split_symbol(c)
    c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym
  when SQL::AliasedExpression
    c.expression
  when SQL::OrderedExpression
    case expr = c.expression
    when Symbol, SQL::AliasedExpression
      SQL::OrderedExpression.new(unaliased_identifier(expr), c.descending, :nulls=>c.nulls)
    else
      c
    end
  else
    c
  end
end

3 - User Methods relating to SQL Creation

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Public Instance Methods

delete_sql() click to toggle source

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
def delete_sql
  return static_sql(opts[:sql]) if opts[:sql]
  check_modification_allowed!
  clause_sql(:delete)
end
exists() click to toggle source

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
def exists
  SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
end
insert_sql(*values) click to toggle source

Returns an INSERT SQL query string. See insert.

DB[:items].insert_sql(:a=>1)
# => "INSERT INTO items (a) VALUES (1)"
# File lib/sequel/dataset/sql.rb, line 30
def insert_sql(*values)
  return static_sql(@opts[:sql]) if @opts[:sql]

  check_modification_allowed!

  columns = []

  case values.size
  when 0
    return insert_sql({})
  when 1
    case vals = values.at(0)
    when Hash
      vals = @opts[:defaults].merge(vals) if @opts[:defaults]
      vals = vals.merge(@opts[:overrides]) if @opts[:overrides]
      values = []
      vals.each do |k,v| 
        columns << k
        values << v
      end
    when Dataset, Array, LiteralString
      values = vals
    end
  when 2
    if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
      columns, values = v0, v1
      raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
    end
  end

  if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
    columns = [columns().last]
    values = [DEFAULT]
  end
  clone(:columns=>columns, :values=>values)._insert_sql
end
literal_append(sql, v) click to toggle source

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 77
def literal_append(sql, v)
  case v
  when Symbol
    literal_symbol_append(sql, v)
  when String
    case v
    when LiteralString
      sql << v
    when SQL::Blob
      literal_blob_append(sql, v)
    else
      literal_string_append(sql, v)
    end
  when Integer
    sql << literal_integer(v)
  when Hash
    literal_hash_append(sql, v)
  when SQL::Expression
    literal_expression_append(sql, v)
  when Float
    sql << literal_float(v)
  when BigDecimal
    sql << literal_big_decimal(v)
  when NilClass
    sql << literal_nil
  when TrueClass
    sql << literal_true
  when FalseClass
    sql << literal_false
  when Array
    literal_array_append(sql, v)
  when Time
    sql << (v.is_a?(SQLTime) ? literal_sqltime(v) : literal_time(v))
  when DateTime
    sql << literal_datetime(v)
  when Date
    sql << literal_date(v)
  when Dataset
    literal_dataset_append(sql, v)
  else
    literal_other_append(sql, v)
  end
end
multi_insert_sql(columns, values) click to toggle source

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

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 127
def multi_insert_sql(columns, values)
  values.map{|r| insert_sql(columns, r)}
end
select_sql() click to toggle source

Returns a SELECT SQL query string.

dataset.select_sql # => "SELECT * FROM items"
# File lib/sequel/dataset/sql.rb, line 134
def select_sql
  return static_sql(@opts[:sql]) if @opts[:sql]
  clause_sql(:select)
end
sql() click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 140
def sql
  select_sql
end
truncate_sql() click to toggle source

Returns a TRUNCATE SQL query string. See truncate

DB[:items].truncate_sql # => 'TRUNCATE items'
# File lib/sequel/dataset/sql.rb, line 147
def truncate_sql
  if opts[:sql]
    static_sql(opts[:sql])
  else
    check_truncation_allowed!
    raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
    t = ''
    source_list_append(t, opts[:from])
    _truncate_sql(t)
  end
end
update_sql(values = {}) click to toggle source

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

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

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

# File lib/sequel/dataset/sql.rb, line 166
def update_sql(values = {})
  return static_sql(opts[:sql]) if opts[:sql]
  check_modification_allowed!
  clone(:values=>values)._update_sql
end

4 - Methods that describe what the dataset supports

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Public Instance Methods

provides_accurate_rows_matched?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 23
def provides_accurate_rows_matched?
  true
end
quote_identifiers?() click to toggle source

Whether this dataset quotes identifiers.

# File lib/sequel/dataset/features.rb, line 10
def quote_identifiers?
  if defined?(@quote_identifiers)
    @quote_identifiers
  elsif db.respond_to?(:quote_identifiers?)
    @quote_identifiers = db.quote_identifiers?
  else
    @quote_identifiers = false
  end
end
recursive_cte_requires_column_aliases?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 29
def recursive_cte_requires_column_aliases?
  false
end
requires_placeholder_type_specifiers?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 41
def requires_placeholder_type_specifiers?
  false
end
requires_sql_standard_datetimes?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 35
def requires_sql_standard_datetimes?
  false
end
supports_cte?(type=:select) click to toggle source

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
def supports_cte?(type=:select)
  send(:"#{type}_clause_methods").include?(:"#{type}_with_sql")
end
supports_cte_in_subqueries?() click to toggle source

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
def supports_cte_in_subqueries?
  false
end
supports_distinct_on?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 60
def supports_distinct_on?
  false
end
supports_group_cube?() click to toggle source

Whether the dataset supports CUBE with GROUP BY.

# File lib/sequel/dataset/features.rb, line 65
def supports_group_cube?
  false
end
supports_group_rollup?() click to toggle source

Whether the dataset supports ROLLUP with GROUP BY.

# File lib/sequel/dataset/features.rb, line 70
def supports_group_rollup?
  false
end
supports_insert_select?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 76
def supports_insert_select?
  supports_returning?(:insert)
end
supports_intersect_except?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 81
def supports_intersect_except?
  true
end
supports_intersect_except_all?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 86
def supports_intersect_except_all?
  true
end
supports_is_true?() click to toggle source

Whether the dataset supports the IS TRUE syntax.

# File lib/sequel/dataset/features.rb, line 91
def supports_is_true?
  true
end
supports_join_using?() click to toggle source

Whether the dataset supports the JOIN table USING (column1, …) syntax.

# File lib/sequel/dataset/features.rb, line 96
def supports_join_using?
  true
end
supports_modifying_joins?() click to toggle source

Whether modifying joined datasets is supported.

# File lib/sequel/dataset/features.rb, line 101
def supports_modifying_joins?
  false
end
supports_multiple_column_in?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 107
def supports_multiple_column_in?
  true
end
supports_ordered_distinct_on?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 113
def supports_ordered_distinct_on?
  supports_distinct_on?
end
supports_regexp?() click to toggle source

Whether the dataset supports pattern matching by regular expressions.

# File lib/sequel/dataset/features.rb, line 118
def supports_regexp?
  false
end
supports_returning?(type) click to toggle source

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 124
def supports_returning?(type)
  send(:"#{type}_clause_methods").include?(:"#{type}_returning_sql")
end
supports_select_all_and_column?() click to toggle source

Whether the database supports SELECT *, column FROM table

# File lib/sequel/dataset/features.rb, line 129
def supports_select_all_and_column?
  true
end
supports_timestamp_timezones?() click to toggle source

Whether the dataset supports timezones in literal timestamps

# File lib/sequel/dataset/features.rb, line 134
def supports_timestamp_timezones?
  false
end
supports_timestamp_usecs?() click to toggle source

Whether the dataset supports fractional seconds in literal timestamps

# File lib/sequel/dataset/features.rb, line 139
def supports_timestamp_usecs?
  true
end
supports_where_true?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 150
def supports_where_true?
  true
end
supports_window_functions?() click to toggle source

Whether the dataset supports window functions.

# File lib/sequel/dataset/features.rb, line 144
def supports_window_functions?
  false
end

Private Instance Methods

insert_supports_empty_values?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 158
def insert_supports_empty_values?
  true
end
uses_returning?(type) click to toggle source

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

# File lib/sequel/dataset/features.rb, line 164
def uses_returning?(type)
  opts[:returning] && !@opts[:sql] && supports_returning?(type)
end
uses_with_rollup?() click to toggle source

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

# File lib/sequel/dataset/features.rb, line 169
def uses_with_rollup?
  false
end

5 - Methods related to dataset graphing

↑ top

Public Instance Methods

add_graph_aliases(graph_aliases) click to toggle source

Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list (the equivalent of select_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
def add_graph_aliases(graph_aliases)
  columns, graph_aliases = graph_alias_columns(graph_aliases)
  ds = select_more(*columns)
  ds.opts[:graph_aliases] = (ds.opts[:graph_aliases] || (ds.opts[:graph][:column_aliases] rescue {}) || {}).merge(graph_aliases)
  ds
end
graph(dataset, join_conditions = nil, options = {}, &block) click to toggle source

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.

:qualify

The type of qualification to do, see join_table.

:select

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

:table_alias

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

# File lib/sequel/dataset/graph.rb, line 75
def graph(dataset, join_conditions = nil, options = {}, &block)
  # Allow the use of a dataset or symbol as the first argument
  # Find the table name/dataset based on the argument
  table_alias = options[:table_alias]
  case dataset
  when Symbol
    table = dataset
    dataset = @db[dataset]
    table_alias ||= table
  when ::Sequel::Dataset
    if dataset.simple_select_all?
      table = dataset.opts[:from].first
      table_alias ||= table
    else
      table = dataset
      table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
    end
  else
    raise Error, "The dataset argument should be a symbol or dataset"
  end

  # Raise Sequel::Error with explanation that the table alias has been used
  raise_alias_error = lambda do
    raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify "            "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
  end

  # Only allow table aliases that haven't been used
  raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
  
  # Use a from_self if this is already a joined table
  ds = (!@opts[:graph] && (@opts[:from].length > 1 || @opts[:join])) ? from_self(:alias=>options[:from_self_alias] || first_source) : self
  
  # Join the table early in order to avoid cloning the dataset twice
  ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias, :implicit_qualifier=>options[:implicit_qualifier], :qualify=>options[:qualify], &block)
  opts = ds.opts

  # Whether to include the table in the result set
  add_table = options[:select] == false ? false : true
  # Whether to add the columns to the list of column aliases
  add_columns = !ds.opts.include?(:graph_aliases)

  # Setup the initial graph data structure if it doesn't exist
  if graph = opts[:graph]
    opts[:graph] = graph = graph.dup
    select = opts[:select].dup
    [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
  else
    master = alias_symbol(ds.first_source_alias)
    raise_alias_error.call if master == table_alias
    # Master hash storing all .graph related information
    graph = opts[:graph] = {}
    # Associates column aliases back to tables and columns
    column_aliases = graph[:column_aliases] = {}
    # Associates table alias (the master is never aliased)
    table_aliases = graph[:table_aliases] = {master=>self}
    # Keep track of the alias numbers used
    ca_num = graph[:column_alias_num] = Hash.new(0)
    # All columns in the master table are never
    # aliased, but are not included if set_graph_aliases
    # has been used.
    if add_columns
      if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll)))
        select = select.each do |sel|
          column = case sel
          when Symbol
            _, c, a = split_symbol(sel)
            (a || c).to_sym
          when SQL::Identifier
            sel.value.to_sym
          when SQL::QualifiedIdentifier
            column = sel.column
            column = column.value if column.is_a?(SQL::Identifier)
            column.to_sym
          when SQL::AliasedExpression
            column = sel.aliaz
            column = column.value if column.is_a?(SQL::Identifier)
            column.to_sym
          else
            raise Error, "can't figure out alias to use for graphing for #{sel.inspect}"
          end
          column_aliases[column] = [master, column]
        end
        select = qualified_expression(select, master)
      else
        select = columns.map do |column|
          column_aliases[column] = [master, column]
          SQL::QualifiedIdentifier.new(master, column)
        end
      end
    end
  end

  # Add the table alias to the list of aliases
  # Even if it isn't been used in the result set,
  # we add a key for it with a nil value so we can check if it
  # is used more than once
  table_aliases = graph[:table_aliases]
  table_aliases[table_alias] = add_table ? dataset : nil

  # Add the columns to the selection unless we are ignoring them
  if add_table && add_columns
    column_aliases = graph[:column_aliases]
    ca_num = graph[:column_alias_num]
    # Which columns to add to the result set
    cols = options[:select] || dataset.columns
    # If the column hasn't been used yet, don't alias it.
    # If it has been used, try table_column.
    # If that has been used, try table_column_N 
    # using the next value of N that we know hasn't been
    # used
    cols.each do |column|
      col_alias, identifier = if column_aliases[column]
        column_alias = :"#{table_alias}_#{column}"
        if column_aliases[column_alias]
          column_alias_num = ca_num[column_alias]
          column_alias = :"#{column_alias}_#{column_alias_num}" 
          ca_num[column_alias] += 1
        end
        [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias, column), column_alias)]
      else
        ident = SQL::QualifiedIdentifier.new(table_alias, column)
        [column, ident]
      end
      column_aliases[col_alias] = [table_alias, column]
      select.push(identifier)
    end
  end
  add_columns ? ds.select(*select) : ds
end
set_graph_aliases(graph_aliases) click to toggle source

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

graph_aliases

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

DB[:artists].graph(:albums, :artist_id=>:id).
  set_graph_aliases(:name=>:artists,
                    :album_name=>[:albums, :name],
                    :forty_two=>[:albums, :fourtwo, 42]).first
# SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
# => {:artists=>{:name=>artists.name}, :albums=>{:name=>albums.name, :fourtwo=>42}}
# File lib/sequel/dataset/graph.rb, line 230
def set_graph_aliases(graph_aliases)
  columns, graph_aliases = graph_alias_columns(graph_aliases)
  ds = select(*columns)
  ds.opts[:graph_aliases] = graph_aliases
  ds
end
ungraphed() click to toggle source

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

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

Private Instance Methods

graph_alias_columns(graph_aliases) click to toggle source

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

# File lib/sequel/dataset/graph.rb, line 248
def graph_alias_columns(graph_aliases)
  gas = {}
  identifiers = graph_aliases.collect do |col_alias, tc| 
    table, column, value = Array(tc)
    column ||= col_alias
    gas[col_alias] = [table, column]
    identifier = value || SQL::QualifiedIdentifier.new(table, column)
    identifier = SQL::AliasedExpression.new(identifier, col_alias) if value || column != col_alias
    identifier
  end
  [identifiers, gas]
end
graph_each() { |graph| ... } click to toggle source

Fetch the rows, split them into component table parts, tranform and run the #row_proc on each part (if applicable), and yield a hash of the parts.

# File lib/sequel/dataset/graph.rb, line 264
def graph_each
  # Reject tables with nil datasets, as they are excluded from
  # the result set
  datasets = @opts[:graph][:table_aliases].to_a.reject{|ta,ds| ds.nil?}
  # Get just the list of table aliases into a local variable, for speed
  table_aliases = datasets.collect{|ta,ds| ta}
  # Get an array of arrays, one for each dataset, with
  # the necessary information about each dataset, for speed
  datasets = datasets.collect{|ta, ds| [ta, ds, ds.row_proc]}
  # Use the manually set graph aliases, if any, otherwise
  # use the ones automatically created by .graph
  column_aliases = @opts[:graph_aliases] || @opts[:graph][:column_aliases]
  fetch_rows(select_sql) do |r|
    graph = {}
    # Create the sub hashes, one per table
    table_aliases.each{|ta| graph[ta]={}}
    # Split the result set based on the column aliases
    # If there are columns in the result set that are
    # not in column_aliases, they are ignored
    column_aliases.each do |col_alias, tc|
      ta, column = tc
      graph[ta][column] = r[col_alias]
    end
    # For each dataset run the row_proc if applicable
    datasets.each do |ta,ds,rp|
      g = graph[ta]
      graph[ta] = if g.values.any?{|x| !x.nil?}
        rp ? rp.call(g) : g
      else
        nil
      end
    end

    yield graph
  end
  self
end

6 - Miscellaneous methods

↑ top

Constants

ARG_BLOCK_ERROR_MSG
ARRAY_ACCESS_ERROR_MSG
IMPORT_ERROR_MSG
NOTIMPL_MSG

Attributes

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.

Public Class Methods

new(db, opts = nil) click to toggle source

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

DB[:posts]

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

# File lib/sequel/dataset/misc.rb, line 28
def initialize(db, opts = nil)
  @db = db
  @opts = opts || {}
end

Public Instance Methods

==(o) click to toggle source

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

# File lib/sequel/dataset/misc.rb, line 35
def ==(o)
  o.is_a?(self.class) && db == o.db && opts == o.opts && sql == o.sql
end
each_server() { |server(s)| ... } click to toggle source

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

DB[:configs].where(:key=>'setting').each_server{|ds| ds.update(:value=>'new_value')}
# File lib/sequel/dataset/misc.rb, line 49
def each_server
  db.servers.each{|s| yield server(s)}
end
eql?(o) click to toggle source

Alias for ==

# File lib/sequel/dataset/misc.rb, line 40
def eql?(o)
  self == o
end
escape_like(string) click to toggle source

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

ds.escape_like("foo\\%_") # 'foo\\\%\_'
# File lib/sequel/dataset/misc.rb, line 58
def escape_like(string)
  string.gsub(/[\%_]/){|m| "\\#{m}"}
end
first_source() click to toggle source

Alias of first_source_alias

# File lib/sequel/dataset/misc.rb, line 63
def first_source
  first_source_alias
end
first_source_alias() click to toggle source

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

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

DB[:table___t].first_source_alias
# => :t
# File lib/sequel/dataset/misc.rb, line 75
def first_source_alias
  source = @opts[:from]
  if source.nil? || source.empty?
    raise Error, 'No source specified for query'
  end
  case s = source.first
  when SQL::AliasedExpression
    s.aliaz
  when Symbol
    _, _, aliaz = split_symbol(s)
    aliaz ? aliaz.to_sym : s
  else
    s
  end
end
first_source_table() click to toggle source

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

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

DB[:table___t].first_source_table
# => :table
# File lib/sequel/dataset/misc.rb, line 100
def first_source_table
  source = @opts[:from]
  if source.nil? || source.empty?
    raise Error, 'No source specified for query'
  end
  case s = source.first
  when SQL::AliasedExpression
    s.expression
  when Symbol
    sch, table, aliaz = split_symbol(s)
    aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
  else
    s
  end
end
hash() click to toggle source

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

# File lib/sequel/dataset/misc.rb, line 118
def hash
  [db, opts, sql].hash
end
identifier_input_method() click to toggle source

The String instance method to call on identifiers before sending them to the database.

# File lib/sequel/dataset/misc.rb, line 124
def identifier_input_method
  if defined?(@identifier_input_method)
    @identifier_input_method
  elsif db.respond_to?(:identifier_input_method)
    @identifier_input_method = db.identifier_input_method
  else
    @identifier_input_method = nil
  end
end
identifier_output_method() click to toggle source

The String instance method to call on identifiers before sending them to the database.

# File lib/sequel/dataset/misc.rb, line 136
def identifier_output_method
  if defined?(@identifier_output_method)
    @identifier_output_method
  elsif db.respond_to?(:identifier_output_method)
    @identifier_output_method = db.identifier_output_method
  else
    @identifier_output_method = nil
  end
end
inspect() click to toggle source

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

# File lib/sequel/dataset/misc.rb, line 148
def inspect
  c = self.class
  c = c.superclass while c.name.nil? || c.name == ''
  "#<#{c.name}: #{sql.inspect}>"
end
row_number_column() click to toggle source

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

# File lib/sequel/dataset/misc.rb, line 156
def row_number_column
  :x_sequel_row_number_x
end
split_alias(c) click to toggle source

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

# File lib/sequel/dataset/misc.rb, line 163
def split_alias(c)
  case c
  when Symbol
    c_table, column, aliaz = split_symbol(c)
    [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
  when SQL::AliasedExpression
    [c.expression, c.aliaz]
  when SQL::JoinClause
    [c.table, c.table_alias]
  else
    [c, nil]
  end
end
unused_table_alias(table_alias, used_aliases = []) click to toggle source

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

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

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

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

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

DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2])
# => :table_3
# File lib/sequel/dataset/misc.rb, line 199
def unused_table_alias(table_alias, used_aliases = [])
  table_alias = alias_symbol(table_alias)
  used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
  used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
  if used_aliases.include?(table_alias)
    i = 0
    loop do
      ta = :"#{table_alias}_#{i}"
      return ta unless used_aliases.include?(ta)
      i += 1 
    end
  else
    table_alias
  end
end

7 - Mutation methods

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Constants

MUTATION_METHODS

All methods that should have a ! method added that modifies the receiver.

Attributes

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.

Public Class Methods

def_mutation_method(*meths) click to toggle source

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.

Do not call this method with untrusted input, as that can result in arbitrary code execution.

# File lib/sequel/dataset/mutation.rb, line 17
def self.def_mutation_method(*meths)
  options = meths.pop if meths.last.is_a?(Hash)
  mod = options[:module] if options
  mod ||= self
  meths.each do |meth|
    mod.class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__)
  end
end

Public Instance Methods

extension!(*exts) click to toggle source

Load an extension into the receiver. In addition to requiring the extension file, this also modifies the dataset to work with the extension (usually extending it with a module defined in the extension file). If no related extension file exists or the extension does not have specific support for Database objects, an Error will be raised. Returns self.

# File lib/sequel/dataset/mutation.rb, line 47
def extension!(*exts)
  Sequel.extension(*exts)
  exts.each do |ext|
    if pr = Sequel.synchronize{EXTENSIONS[ext]}
      pr.call(self)
    else
      raise(Error, "Extension #{ext} does not have specific support handling individual datasets")
    end
  end
  self
end
from_self!(*args, &block) click to toggle source

Avoid self-referential dataset by cloning.

# File lib/sequel/dataset/mutation.rb, line 60
def from_self!(*args, &block)
  @opts.merge!(clone.from_self(*args, &block).opts)
  self
end
naked!() click to toggle source

Remove the #row_proc from the current dataset.

# File lib/sequel/dataset/mutation.rb, line 66
def naked!
  self.row_proc = nil
  self
end

Private Instance Methods

mutation_method(meth, *args, &block) click to toggle source

Modify the receiver with the results of sending the meth, args, and block to the receiver and merging the options of the resulting dataset into the receiver's options.

# File lib/sequel/dataset/mutation.rb, line 76
def mutation_method(meth, *args, &block)
  copy = send(meth, *args, &block)
  @opts.merge!(copy.opts)
  self
end

8 - Methods related to prepared statements or bound variables

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Constants

PREPARED_ARG_PLACEHOLDER

Public Instance Methods

bind(bind_vars={}) click to toggle source

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

DB[:table].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 217
def bind(bind_vars={})
  clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars)
end
call(type, bind_variables={}, *values, &block) click to toggle source

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

DB[:table].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 228
def call(type, bind_variables={}, *values, &block)
  prepare(type, nil, *values).call(bind_variables, &block)
end
prepare(type, name=nil, *values) click to toggle source

Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement. 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 250
def prepare(type, name=nil, *values)
  ps = to_prepared_statement(type, values)
  db.set_prepared_statement(name, ps) if name
  ps
end

Protected Instance Methods

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

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

# File lib/sequel/dataset/prepared_statements.rb, line 260
def to_prepared_statement(type, values=nil)
  ps = bind
  ps.extend(PreparedStatementMethods)
  ps.orig_dataset = self
  ps.prepared_type = type
  ps.prepared_modify_values = values
  ps
end

Private Instance Methods

prepared_arg_placeholder() click to toggle source

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

# File lib/sequel/dataset/prepared_statements.rb, line 273
def prepared_arg_placeholder
  PREPARED_ARG_PLACEHOLDER
end

9 - Internal Methods relating to SQL Creation

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Constants

ALL
AND_SEPARATOR
APOS
APOS_RE
ARRAY_EMPTY
AS
ASC
BACKSLASH
BOOL_FALSE
BOOL_TRUE
BRACKET_CLOSE
BRACKET_OPEN
CASE_ELSE
CASE_END
CASE_OPEN
CASE_THEN
CASE_WHEN
CAST_OPEN
COLUMN_REF_RE1
COLUMN_REF_RE2
COLUMN_REF_RE3
COMMA
COMMA_SEPARATOR
CONDITION_FALSE
CONDITION_TRUE
COUNT_FROM_SELF_OPTS
COUNT_OF_ALL_AS_COUNT
DATASET_ALIAS_BASE_NAME
DEFAULT
DEFAULT_VALUES
DELETE
DELETE_CLAUSE_METHODS
DESC
DISTINCT
DOT
DOUBLE_APOS
DOUBLE_QUOTE
EMULATED_FUNCTION_MAP

Map of emulated function names to native function names.

EQUAL
ESCAPE
EXISTS
EXTRACT
FORMAT_DATE
FORMAT_DATE_STANDARD
FORMAT_OFFSET
FORMAT_TIMESTAMP_RE
FORMAT_TIMESTAMP_USEC
FORMAT_USEC
FOR_UPDATE
FRAME_ALL
FRAME_ROWS
FROM
FUNCTION_EMPTY
GROUP_BY
HAVING
INSERT
INSERT_CLAUSE_METHODS
INTO
IS_LITERALS
IS_OPERATORS
LIKE_OPERATORS
LIMIT
NOT_SPACE
NULL
NULLS_FIRST
NULLS_LAST
N_ARITY_OPERATORS
OFFSET
ON
ON_PAREN
ORDER_BY
ORDER_BY_NS
OVER
PAREN_CLOSE
PAREN_OPEN
PAREN_SPACE_OPEN
PARTITION_BY
PRIVATE_APPEND_METHODS
PUBLIC_APPEND_METHODS
QUALIFY_KEYS
QUESTION_MARK
QUESTION_MARK_RE
QUOTE
QUOTE_RE
REGEXP_OPERATORS
RETURNING
SELECT
SELECT_CLAUSE_METHODS
SET
SPACE
SPACE_WITH
SQL_WITH
STANDARD_TIMESTAMP_FORMAT
TILDE
TIMESTAMP_FORMAT
TWO_ARITY_OPERATORS
UNDERSCORE
UPDATE
UPDATE_CLAUSE_METHODS
USING
V190
VALUES
WHERE
WILDCARD

Public Class Methods

clause_methods(type, clauses) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 179
def self.clause_methods(type, clauses)
  clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
end
def_append_methods(meths) click to toggle source

For each of the methods in the given array, define a method with that name that returns a string with the SQL fragment that the related *_append method would add.

Do not call this method with untrusted input, as that can result in arbitrary code execution.

# File lib/sequel/dataset/sql.rb, line 338
    def self.def_append_methods(meths)
      meths.each do |meth|
        class_eval("          def #{meth}(*args, &block)
            s = ''
            #{meth}_append(s, *args, &block)
            s
          end
", __FILE__, __LINE__ + 1)
      end
    end
introspect_all_columns() click to toggle source

Enable column introspection for every dataset.

# File lib/sequel/extensions/columns_introspection.rb, line 89
def self.introspect_all_columns
  include ColumnsIntrospection
  remove_method(:columns) if instance_methods(false).map{|x| x.to_s}.include?('columns')
end

Public Instance Methods

aliased_expression_sql_append(sql, ae) click to toggle source

SQL fragment for AliasedExpression

# File lib/sequel/dataset/sql.rb, line 353
def aliased_expression_sql_append(sql, ae)
  literal_append(sql, ae.expression)
  as_sql_append(sql, ae.aliaz)
end
array_sql_append(sql, a) click to toggle source

SQL fragment for Array

# File lib/sequel/dataset/sql.rb, line 359
def array_sql_append(sql, a)
  if a.empty?
    sql << ARRAY_EMPTY
  else
    sql << PAREN_OPEN
    expression_list_append(sql, a)
    sql << PAREN_CLOSE
  end
end
boolean_constant_sql_append(sql, constant) click to toggle source

SQL fragment for BooleanConstants

# File lib/sequel/dataset/sql.rb, line 370
def boolean_constant_sql_append(sql, constant)
  if (constant == true || constant == false) && !supports_where_true?
    sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE)
  else
    literal_append(sql, constant)
  end
end
case_expression_sql_append(sql, ce) click to toggle source

SQL fragment for CaseExpression

# File lib/sequel/dataset/sql.rb, line 379
def case_expression_sql_append(sql, ce)
  sql << CASE_OPEN
  if ce.expression?
    sql << SPACE
    literal_append(sql, ce.expression)
  end
  w = CASE_WHEN
  t = CASE_THEN
  ce.conditions.each do |c,r|
    sql << w
    literal_append(sql, c)
    sql << t
    literal_append(sql, r)
  end
  sql << CASE_ELSE
  literal_append(sql, ce.default)
  sql << CASE_END
end
cast_sql_append(sql, expr, type) click to toggle source

SQL fragment for the SQL CAST expression

# File lib/sequel/dataset/sql.rb, line 399
def cast_sql_append(sql, expr, type)
  sql << CAST_OPEN
  literal_append(sql, expr)
  sql << AS << db.cast_type_literal(type).to_s
  sql << PAREN_CLOSE
end
column_all_sql_append(sql, ca) click to toggle source

SQL fragment for specifying all columns in a given table

# File lib/sequel/dataset/sql.rb, line 407
def column_all_sql_append(sql, ca)
  qualified_identifier_sql_append(sql, ca.table, WILDCARD)
end
columns_without_introspection()
Alias for: columns
complex_expression_sql_append(sql, op, args) click to toggle source

SQL fragment for the complex expression.

# File lib/sequel/dataset/sql.rb, line 412
def complex_expression_sql_append(sql, op, args)
  case op
  when *IS_OPERATORS
    r = args.at(1)
    if r.nil? || supports_is_true?
      raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r]
      sql << PAREN_OPEN
      literal_append(sql, args.at(0))
      sql << SPACE << op.to_s << SPACE
      sql << val << PAREN_CLOSE
    elsif op == :IS
      complex_expression_sql_append(sql, :"=", args)
    else
      complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)])
    end
  when :IN, :"NOT IN"
    cols = args.at(0)
    vals = args.at(1)
    col_array = true if cols.is_a?(Array)
    if vals.is_a?(Array)
      val_array = true
      empty_val_array = vals == []
    end
    if empty_val_array
      literal_append(sql, empty_array_value(op, cols))
    elsif col_array
      if !supports_multiple_column_in?
        if val_array
          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]})})
          literal_append(sql, op == :IN ? expr : ~expr)
        else
          old_vals = vals
          vals = vals.naked if vals.is_a?(Sequel::Dataset)
          vals = vals.to_a
          val_cols = old_vals.columns
          complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
        end
      else
        # If the columns and values are both arrays, use array_sql instead of
        # literal so that if values is an array of two element arrays, it
        # will be treated as a value list instead of a condition specifier.
        sql << PAREN_OPEN
        literal_append(sql, cols)
        sql << SPACE << op.to_s << SPACE
        if val_array
          array_sql_append(sql, vals)
        else
          literal_append(sql, vals)
        end
        sql << PAREN_CLOSE
      end
    else
      sql << PAREN_OPEN
      literal_append(sql, cols)
      sql << SPACE << op.to_s << SPACE
      literal_append(sql, vals)
      sql << PAREN_CLOSE
    end
  when :LIKE, :'NOT LIKE'
    sql << PAREN_OPEN
    literal_append(sql, args.at(0))
    sql << SPACE << op.to_s << SPACE
    literal_append(sql, args.at(1))
    sql << ESCAPE
    literal_append(sql, BACKSLASH)
    sql << PAREN_CLOSE
  when :ILIKE, :'NOT ILIKE'
    complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
  when *TWO_ARITY_OPERATORS
    if REGEXP_OPERATORS.include?(op) && !supports_regexp?
      raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
    end
    sql << PAREN_OPEN
    literal_append(sql, args.at(0))
    sql << SPACE << op.to_s << SPACE
    literal_append(sql, args.at(1))
    sql << PAREN_CLOSE
  when *N_ARITY_OPERATORS
    sql << PAREN_OPEN
    c = false
    op_str = " #{op} "
    args.each do |a|
      sql << op_str if c
      literal_append(sql, a)
      c ||= true
    end
    sql << PAREN_CLOSE
  when :NOT
    sql << NOT_SPACE
    literal_append(sql, args.at(0))
  when :NOOP
    literal_append(sql, args.at(0))
  when :'B~'
    sql << TILDE
    literal_append(sql, args.at(0))
  when :extract
    sql << EXTRACT << args.at(0).to_s << FROM
    literal_append(sql, args.at(1))
    sql << PAREN_CLOSE
  else
    raise(InvalidOperation, "invalid operator #{op}")
  end
end
constant_sql_append(sql, constant) click to toggle source

SQL fragment for constants

# File lib/sequel/dataset/sql.rb, line 517
def constant_sql_append(sql, constant)
  sql << constant.to_s
end
delayed_evaluation_sql_append(sql, callable) click to toggle source

SQL fragment for delayed evaluations, evaluating the object and literalizing the returned value.

# File lib/sequel/dataset/sql.rb, line 523
def delayed_evaluation_sql_append(sql, callable)
  literal_append(sql, callable.call)
end
each_page(page_size) { |paginate(page_no, page_size, record_count)| ... } click to toggle source

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 26
def each_page(page_size)
  raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit]
  record_count = count
  total_pages = (record_count / page_size.to_f).ceil
  (1..total_pages).each{|page_no| yield paginate(page_no, page_size, record_count)}
  self
end
emulated_function_sql_append(sql, f) click to toggle source

SQL fragment specifying an emulated SQL function call. By default, assumes just the function name may need to be emulated, adapters should set an EMULATED_FUNCTION_MAP hash mapping emulated functions to native functions in their dataset class to setup the emulation.

# File lib/sequel/dataset/sql.rb, line 532
def emulated_function_sql_append(sql, f)
  _function_sql_append(sql, native_function_name(f.f), f.args)
end
function_sql_append(sql, f) click to toggle source

SQL fragment specifying an SQL function call without emulation.

# File lib/sequel/dataset/sql.rb, line 537
def function_sql_append(sql, f)
  _function_sql_append(sql, f.f, f.args)
end
join_clause_sql_append(sql, jc) click to toggle source

SQL fragment specifying a JOIN clause without ON or USING.

# File lib/sequel/dataset/sql.rb, line 542
def join_clause_sql_append(sql, jc)
  table = jc.table
  table_alias = jc.table_alias
  table_alias = nil if table == table_alias
  sql << SPACE << join_type_sql(jc.join_type) << SPACE
  identifier_append(sql, table)
  as_sql_append(sql, table_alias) if table_alias
end
join_on_clause_sql_append(sql, jc) click to toggle source

SQL fragment specifying a JOIN clause with ON.

# File lib/sequel/dataset/sql.rb, line 552
def join_on_clause_sql_append(sql, jc)
  join_clause_sql_append(sql, jc)
  sql << ON
  literal_append(sql, filter_expr(jc.on))
end
join_using_clause_sql_append(sql, jc) click to toggle source

SQL fragment specifying a JOIN clause with USING.

# File lib/sequel/dataset/sql.rb, line 559
def join_using_clause_sql_append(sql, jc)
  join_clause_sql_append(sql, jc)
  sql << USING
  column_list_append(sql, jc.using)
  sql << PAREN_CLOSE
end
negative_boolean_constant_sql_append(sql, constant) click to toggle source

SQL fragment for NegativeBooleanConstants

# File lib/sequel/dataset/sql.rb, line 567
def negative_boolean_constant_sql_append(sql, constant)
  sql << NOT_SPACE
  boolean_constant_sql_append(sql, constant)
end
nullify() click to toggle source

Return a cloned nullified dataset.

# File lib/sequel/extensions/null_dataset.rb, line 87
def nullify
  clone.nullify!
end
nullify!() click to toggle source

Nullify the current dataset

# File lib/sequel/extensions/null_dataset.rb, line 92
def nullify!
  extend NullDataset
end
ordered_expression_sql_append(sql, oe) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 574
def ordered_expression_sql_append(sql, oe)
  literal_append(sql, oe.expression)
  sql << (oe.descending ? DESC : ASC)
  case oe.nulls
  when :first
    sql << NULLS_FIRST
  when :last
    sql << NULLS_LAST
  end
end
paginate(page_no, page_size, record_count=nil) click to toggle source

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 17
def paginate(page_no, page_size, record_count=nil)
  raise(Error, "You cannot paginate a dataset that already has a limit") if @opts[:limit]
  paginated = limit(page_size, (page_no - 1) * page_size)
  paginated.extend(Pagination)
  paginated.set_pagination_info(page_no, page_size, record_count || count)
end
placeholder_literal_string_sql_append(sql, pls) click to toggle source

SQL fragment for a literal string with placeholders

# File lib/sequel/dataset/sql.rb, line 586
def placeholder_literal_string_sql_append(sql, pls)
  args = pls.args
  str = pls.str
  sql << PAREN_OPEN if pls.parens
  if args.is_a?(Hash)
    re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
    loop do
      previous, q, str = str.partition(re)
      sql << previous
      literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
      break if str.empty?
    end
  elsif str.is_a?(Array)
    len = args.length
    str.each_with_index do |s, i|
      sql << s
      literal_append(sql, args[i]) unless i == len
    end
  else
    i = -1
    loop do
      previous, q, str = str.partition(QUESTION_MARK)
      sql << previous
       literal_append(sql, args.at(i+=1)) unless q.empty?
      break if str.empty?
    end
  end
  sql << PAREN_CLOSE if pls.parens
end
print(*cols) click to toggle source

Pretty prints the records in the dataset as plain-text table.

qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) click to toggle source

SQL fragment for the qualifed identifier, specifying a table and a column (or schema and table). If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.

# File lib/sequel/dataset/sql.rb, line 620
def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
  identifier_append(sql, table)
  sql << DOT
  identifier_append(sql, column)
end
query(&block) click to toggle source

Translates a query block into a dataset. Query blocks are an alternative to Sequel's usual method chaining, by using instance_eval with a proxy object:

dataset = DB[:items].query do
  select :x, :y, :z
  filter{(x > 1) & (y > 2)}
  reverse :z
end

Which is the same as:

dataset = DB[:items].select(:x, :y, :z).filter{(x > 1) & (y > 2)}.reverse(:z)
# File lib/sequel/extensions/query.rb, line 31
def query(&block)
  query = Query.new(self)
  query.instance_eval(&block)
  query.dataset
end
quote_identifier_append(sql, name) click to toggle source

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 629
def quote_identifier_append(sql, name)
  if name.is_a?(LiteralString)
    sql << name
  else
    name = name.value if name.is_a?(SQL::Identifier)
    name = input_identifier(name)
    if quote_identifiers?
      quoted_identifier_append(sql, name)
    else
      sql << name
    end
  end
end
quote_schema_table_append(sql, table) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 645
def quote_schema_table_append(sql, table)
  schema, table = schema_and_table(table)
  if schema
    quote_identifier_append(sql, schema)
    sql << DOT
  end
  quote_identifier_append(sql, table)
end
quoted_identifier_append(sql, name) click to toggle source

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 657
def quoted_identifier_append(sql, name)
  sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE
end
schema_and_table(table_name, sch=(db.default_schema if db)) click to toggle source

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

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

# File lib/sequel/dataset/sql.rb, line 668
def schema_and_table(table_name, sch=(db.default_schema if db))
  sch = sch.to_s if sch
  case table_name
  when Symbol
    s, t, _ = split_symbol(table_name)
    [s||sch, t]
  when SQL::QualifiedIdentifier
    [table_name.table.to_s, table_name.column.to_s]
  when SQL::Identifier
    [sch, table_name.value.to_s]
  when String
    [sch, table_name]
  else
    raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
  end
end
select_remove(*cols) click to toggle source

Remove columns from the list of selected columns. If any of the currently selected columns use expressions/aliases, this will remove selected columns with the given aliases. It will also remove entries from the selection that match exactly:

# Assume columns a, b, and c in items table
DB[:items] # SELECT * FROM items
DB[:items].select_remove(:c) # SELECT a, b FROM items
DB[:items].select(:a, :b___c, :c___b).select_remove(:c) # SELECT a, c AS b FROM items
DB[:items].select(:a, :b___c, :c___b).select_remove(:c___b) # SELECT a, b AS c FROM items

Note that there are a few cases where this method may not work correctly:

  • This dataset joins multiple tables and does not have an existing explicit selection. In this case, the code will currently use unqualified column names for all columns the dataset returns, except for the columns given.

  • This dataset has an existing explicit selection containing an item that returns multiple database columns (e.g. Sequel.expr(:table).*, Sequel.lit('column1, column2')). In this case, the behavior is undefined and this method should not be used.

There may be other cases where this method does not work correctly, use it with caution.

# File lib/sequel/extensions/select_remove.rb, line 31
def select_remove(*cols)
  if (sel = @opts[:select]) && !sel.empty?
    select(*(columns.zip(sel).reject{|c, s| cols.include?(c)}.map{|c, s| s} - cols))
  else
    select(*(columns - cols))
  end
end
split_qualifiers(table_name, *args) click to toggle source

Splits table_name into an array of strings.

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

SQL fragment for specifying subscripts (SQL array accesses)

# File lib/sequel/dataset/sql.rb, line 702
def subscript_sql_append(sql, s)
  literal_append(sql, s.f)
  sql << BRACKET_OPEN
  expression_list_append(sql, s.sub)
  sql << BRACKET_CLOSE
end
to_dot() click to toggle source

Return a string that can be processed by the dot program (included with graphviz) in order to see a visualization of the dataset's abstract syntax tree.

# File lib/sequel/extensions/to_dot.rb, line 149
def to_dot
  ToDot.output(self)
end
window_function_sql_append(sql, function, window) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 751
def window_function_sql_append(sql, function, window)
  literal_append(sql, function)
  sql << OVER
  literal_append(sql, window)
end
window_sql_append(sql, opts) click to toggle source

The SQL fragment for the given window's options.

# File lib/sequel/dataset/sql.rb, line 710
def window_sql_append(sql, opts)
  raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
  sql << PAREN_OPEN
  window, part, order, frame = opts.values_at(:window, :partition, :order, :frame)
  space = false
  space_s = SPACE
  if window
    literal_append(sql, window)
    space = true
  end
  if part
    sql << space_s if space
    sql << PARTITION_BY
    expression_list_append(sql, Array(part))
    space = true
  end
  if order
    sql << space_s if space
    sql << ORDER_BY_NS
    expression_list_append(sql, Array(order))
    space = true
  end
  case frame
    when nil
      # nothing
    when :all
      sql << space_s if space
      sql << FRAME_ALL
    when :rows
      sql << space_s if space
      sql << FRAME_ROWS
    when String
      sql << space_s if space
      sql << frame
    else
      raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil"
  end
  sql << PAREN_CLOSE
end

Protected Instance Methods

_insert_sql() click to toggle source

Formats in INSERT statement using the stored columns and values.

# File lib/sequel/dataset/sql.rb, line 760
def _insert_sql
  clause_sql(:insert)
end
_update_sql() click to toggle source

Formats an UPDATE statement using the stored values.

# File lib/sequel/dataset/sql.rb, line 765
def _update_sql
  clause_sql(:update)
end
compound_from_self() click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 771
def compound_from_self
  (@opts[:limit] || @opts[:order]) ? from_self : self
end

Private Instance Methods

_function_sql_append(sql, name, args) click to toggle source

Backbone of #function_sql_append and emulated_function_sql_append.

# File lib/sequel/dataset/sql.rb, line 778
def _function_sql_append(sql, name, args)
  sql << name.to_s
  if args.empty?
    sql << FUNCTION_EMPTY
  else
    literal_append(sql, args)
  end
end
_truncate_sql(table) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 789
def _truncate_sql(table)
  "TRUNCATE TABLE #{table}"
end
aggregate_dataset() click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 832
def aggregate_dataset
  options_overlap(COUNT_FROM_SELF_OPTS) ? from_self : unordered
end
alias_alias_symbol(s) click to toggle source

Returns an appropriate symbol for the alias represented by s.

# File lib/sequel/dataset/sql.rb, line 794
def alias_alias_symbol(s)
  case s
  when Symbol
    s
  when String
    s.to_sym
  when SQL::Identifier
    s.value.to_s.to_sym
  else
    raise Error, "Invalid alias for alias_alias_symbol: #{s.inspect}"
  end
end
alias_symbol(sym) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 810
def alias_symbol(sym)
  case sym
  when Symbol
    s, t, a = split_symbol(sym)
    a || s ? (a || t).to_sym : sym
  when String
    sym.to_sym
  when SQL::Identifier
    sym.value.to_s.to_sym
  when SQL::QualifiedIdentifier
    alias_symbol(sym.column)
  when SQL::AliasedExpression
    alias_alias_symbol(sym.aliaz)
  else
    raise Error, "Invalid alias for alias_symbol: #{sym.inspect}"
  end
end
as_sql_append(sql, aliaz) click to toggle source

SQL fragment for specifying an alias. expression should already be literalized.

# File lib/sequel/dataset/sql.rb, line 837
def as_sql_append(sql, aliaz)
  sql << AS
  quote_identifier_append(sql, aliaz)
end
check_modification_allowed!() click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 844
def check_modification_allowed!
  raise(InvalidOperation, "Grouped datasets cannot be modified") if opts[:group]
  raise(InvalidOperation, "Joined datasets cannot be modified") if !supports_modifying_joins? && joined_dataset?
end
check_truncation_allowed!() click to toggle source

Alias of check_modification_allowed!

# File lib/sequel/dataset/sql.rb, line 850
def check_truncation_allowed!
  check_modification_allowed!
end
clause_sql(type) click to toggle source

Prepare an SQL statement by calling all clause methods for the given statement type.

# File lib/sequel/dataset/sql.rb, line 855
def clause_sql(type)
  sql = @opts[:append_sql] || sql_string_origin
  send("#{type}_clause_methods").each{|x| send(x, sql)}
  sql
end
column_list_append(sql, columns) click to toggle source

Converts an array of column names into a comma seperated string of column names. If the array is empty, a wildcard (*) is returned.

# File lib/sequel/dataset/sql.rb, line 863
def column_list_append(sql, columns)
  if (columns.nil? || columns.empty?)
    sql << WILDCARD
  else
    expression_list_append(sql, columns)
  end
end
complex_expression_arg_pairs(args) { |at, at| ... } click to toggle source

Yield each two pair of arguments to the block, which should return a string representing the SQL code for those two arguments. If more than 2 arguments are provided, all calls to the block # after the first will have a LiteralString as the first argument, representing the application of the block to the previous arguments.

# File lib/sequel/dataset/sql.rb, line 877
def complex_expression_arg_pairs(args)
  case args.length
  when 1
    literal(args.at(0))
  when 2
    yield args.at(0), args.at(1)
  else
    args.inject{|m, a| LiteralString.new(yield(m, a))}
  end
end
compound_dataset_sql_append(sql, ds) click to toggle source

The SQL to use for the dataset used in a UNION/INTERSECT/EXCEPT clause.

# File lib/sequel/dataset/sql.rb, line 889
def compound_dataset_sql_append(sql, ds)
  subselect_sql_append(sql, ds)
end
dataset_alias(number) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 894
def dataset_alias(number)
  :"#{DATASET_ALIAS_BASE_NAME}#{number}"
end
default_timestamp_format() click to toggle source

The strftime format to use when literalizing the time.

# File lib/sequel/dataset/sql.rb, line 899
def default_timestamp_format
  requires_sql_standard_datetimes? ? STANDARD_TIMESTAMP_FORMAT : TIMESTAMP_FORMAT
end
delete_clause_methods() click to toggle source

The order of methods to call to build the DELETE SQL statement

# File lib/sequel/dataset/sql.rb, line 904
def delete_clause_methods
  DELETE_CLAUSE_METHODS
end
delete_delete_sql(sql) click to toggle source
# File lib/sequel/dataset/sql.rb, line 908
def delete_delete_sql(sql)
  sql << DELETE
end
delete_from_sql(sql)
Alias for: select_from_sql
delete_order_sql(sql)
Alias for: select_order_sql
delete_returning_sql(sql)
delete_where_sql(sql)
Alias for: select_where_sql
delete_with_sql(sql)
Alias for: select_with_sql
empty_array_value(op, cols) click to toggle source
# File lib/sequel/dataset/sql.rb, line 924
def empty_array_value(op, cols)
  if Sequel.empty_array_handle_nulls
    c = Array(cols)
    SQL::BooleanExpression.from_value_pairs(c.zip(c), :AND, op == :IN)
  else
    {1 => ((op == :IN) ? 0 : 1)}
  end
end
expression_list_append(sql, columns) click to toggle source

Converts an array of expressions into a comma separated string of expressions.

# File lib/sequel/dataset/sql.rb, line 914
def expression_list_append(sql, columns)
  c = false
  co = COMMA
  columns.each do |col|
    sql << co if c
    literal_append(sql, col)
    c ||= true
  end
end
format_timestamp(v) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 937
def format_timestamp(v)
  v2 = db.from_application_timestamp(v)
  fmt = default_timestamp_format.gsub(FORMAT_TIMESTAMP_RE) do |m|
    if m == FORMAT_USEC
      format_timestamp_usec(v.is_a?(DateTime) ? v.sec_fraction*(RUBY_VERSION < V190 ? 86400000000 : 1000000) : v.usec) if supports_timestamp_usecs?
    else
      if supports_timestamp_timezones?
        # Would like to just use %z format, but it doesn't appear to work on Windows
        # Instead, the offset fragment is constructed manually
        minutes = (v2.is_a?(DateTime) ? v2.offset * 1440 : v2.utc_offset/60).to_i
        format_timestamp_offset(*minutes.divmod(60))
      end
    end
  end
  v2.strftime(fmt)
end
format_timestamp_offset(hour, minute) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 955
def format_timestamp_offset(hour, minute)
  sprintf(FORMAT_OFFSET, hour, minute)
end
format_timestamp_usec(usec) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 961
def format_timestamp_usec(usec)
  sprintf(FORMAT_TIMESTAMP_USEC, usec)
end
identifier_append(sql, v) click to toggle source

Append the value, but special case regular (non-literal, non-blob) strings so that they are considered as identifiers and not SQL strings.

# File lib/sequel/dataset/sql.rb, line 967
def identifier_append(sql, v)
  if v.is_a?(String)
    case v
    when LiteralString
      sql << v
    when SQL::Blob
      literal_append(sql, v)
    else
      quote_identifier_append(sql, v)
    end
  else
    literal_append(sql, v)
  end
end
Also aliased as: table_ref_append
identifier_list_append(sql, args) click to toggle source

Append all identifiers in args interspersed by commas.

# File lib/sequel/dataset/sql.rb, line 984
def identifier_list_append(sql, args)
  c = false
  comma = COMMA
  args.each do |a|
    sql << comma if c
    identifier_append(sql, a)
    c ||= true
  end
end
input_identifier(v) click to toggle source

Modify the identifier returned from the database based on the identifier_output_method.

# File lib/sequel/dataset/sql.rb, line 996
def input_identifier(v)
  (i = identifier_input_method) ? v.to_s.send(i) : v.to_s
end
insert_clause_methods() click to toggle source

The order of methods to call to build the INSERT SQL statement

# File lib/sequel/dataset/sql.rb, line 1007
def insert_clause_methods
  INSERT_CLAUSE_METHODS
end
insert_columns_sql(sql) click to toggle source

SQL fragment specifying the columns to insert into

# File lib/sequel/dataset/sql.rb, line 1012
def insert_columns_sql(sql)
  columns = opts[:columns]
  if columns && !columns.empty?
    sql << PAREN_SPACE_OPEN
    identifier_list_append(sql, columns)
    sql << PAREN_CLOSE
  end 
end
insert_insert_sql(sql) click to toggle source
# File lib/sequel/dataset/sql.rb, line 1021
def insert_insert_sql(sql)
  sql << INSERT
end
insert_into_sql(sql) click to toggle source

SQL fragment specifying the table to insert INTO

# File lib/sequel/dataset/sql.rb, line 1001
def insert_into_sql(sql)
  sql << INTO
  source_list_append(sql, @opts[:from])
end
insert_returning_sql(sql) click to toggle source

SQL fragment specifying the values to return.

# File lib/sequel/dataset/sql.rb, line 1046
def insert_returning_sql(sql)
  if opts.has_key?(:returning)
    sql << RETURNING
    column_list_append(sql, Array(opts[:returning]))
  end
end
insert_values_sql(sql) click to toggle source

SQL fragment specifying the values to insert.

# File lib/sequel/dataset/sql.rb, line 1026
def insert_values_sql(sql)
  case values = opts[:values]
  when Array
    if values.empty?
      sql << DEFAULT_VALUES
    else
      sql << VALUES
      literal_append(sql, values)
    end
  when Dataset
    sql << SPACE
    subselect_sql_append(sql, values)
  when LiteralString
    sql << SPACE << values
  else
    raise Error, "Unsupported INSERT values type, should be an Array or Dataset: #{values.inspect}"
  end
end
insert_with_sql(sql)
Alias for: select_with_sql
join_type_sql(join_type) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 1057
def join_type_sql(join_type)
  "#{join_type.to_s.gsub(UNDERSCORE, SPACE).upcase} JOIN"
end
joined_dataset?() click to toggle source

Whether this dataset is a joined dataset

# File lib/sequel/dataset/sql.rb, line 1062
def joined_dataset?
 (opts[:from].is_a?(Array) && opts[:from].size > 1) || opts[:join]
end
literal_array_append(sql, v) click to toggle source

SQL fragment for Array. Treats as an expression if an array of all two pairs, or as a SQL array otherwise.

# File lib/sequel/dataset/sql.rb, line 1067
def literal_array_append(sql, v)
  if Sequel.condition_specifier?(v)
    literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
  else
    array_sql_append(sql, v)
  end
end
literal_big_decimal(v) click to toggle source

SQL fragment for BigDecimal

# File lib/sequel/dataset/sql.rb, line 1076
def literal_big_decimal(v)
  d = v.to_s("F")
  v.nan? || v.infinite? ?  "'#{d}'" : d
end
literal_blob_append(sql, v) click to toggle source

SQL fragment for SQL::Blob

# File lib/sequel/dataset/sql.rb, line 1082
def literal_blob_append(sql, v)
  literal_string_append(sql, v)
end
literal_dataset_append(sql, v) click to toggle source

SQL fragment for Dataset. Does a subselect inside parantheses.

# File lib/sequel/dataset/sql.rb, line 1087
def literal_dataset_append(sql, v)
  sql << PAREN_OPEN
  subselect_sql_append(sql, v)
  sql << PAREN_CLOSE
end
literal_date(v) click to toggle source

SQL fragment for Date, using the ISO8601 format.

# File lib/sequel/dataset/sql.rb, line 1094
def literal_date(v)
  if requires_sql_standard_datetimes?
    v.strftime(FORMAT_DATE_STANDARD)
  else
    v.strftime(FORMAT_DATE)
  end
end
literal_datetime(v) click to toggle source

SQL fragment for DateTime

# File lib/sequel/dataset/sql.rb, line 1103
def literal_datetime(v)
  format_timestamp(v)
end
literal_expression_append(sql, v) click to toggle source

SQL fragment for SQL::Expression, result depends on the specific type of expression.

# File lib/sequel/dataset/sql.rb, line 1108
def literal_expression_append(sql, v)
  v.to_s_append(self, sql)
end
literal_false() click to toggle source

SQL fragment for false

# File lib/sequel/dataset/sql.rb, line 1113
def literal_false
  BOOL_FALSE
end
literal_float(v) click to toggle source

SQL fragment for Float

# File lib/sequel/dataset/sql.rb, line 1118
def literal_float(v)
  v.to_s
end
literal_hash_append(sql, v) click to toggle source

SQL fragment for Hash, treated as an expression

# File lib/sequel/dataset/sql.rb, line 1123
def literal_hash_append(sql, v)
  literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
end
literal_integer(v) click to toggle source

SQL fragment for Integer

# File lib/sequel/dataset/sql.rb, line 1128
def literal_integer(v)
  v.to_s
end
literal_nil() click to toggle source

SQL fragment for nil

# File lib/sequel/dataset/sql.rb, line 1133
def literal_nil
  NULL
end
literal_other_append(sql, v) click to toggle source

SQL fragment for a type of object not handled by Dataset#literal. Calls sql_literal if object responds to it, otherwise raises an error. Classes implementing sql_literal should call a class-specific method on the dataset provided and should add that method to Sequel::Dataset, allowing for adapters to provide customized literalizations. If a database specific type is allowed, this should be overriden in a subclass.

# File lib/sequel/dataset/sql.rb, line 1143
def literal_other_append(sql, v)
  if v.respond_to?(:sql_literal_append)
    v.sql_literal_append(self, sql)
  elsif v.respond_to?(:sql_literal)
    sql << v.sql_literal(self)
  else
    raise Error, "can't express #{v.inspect} as a SQL literal"
  end
end
literal_sqltime(v) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 1154
def literal_sqltime(v)
  v.strftime("'%H:%M:%S#{format_timestamp_usec(v.usec) if supports_timestamp_usecs?}'")
end
literal_string_append(sql, v) click to toggle source

SQL fragment for String. Doubles \ and ' by default.

# File lib/sequel/dataset/sql.rb, line 1159
def literal_string_append(sql, v)
  sql << APOS << v.gsub(APOS_RE, DOUBLE_APOS) << APOS
end
literal_symbol_append(sql, v) click to toggle source

Converts a symbol into a column name. This method supports underscore notation in order to express qualified (two underscores) and aliased (three underscores) columns:

dataset.literal(:abc) #=> "abc"
dataset.literal(:abc___a) #=> "abc AS a"
dataset.literal(:items__abc) #=> "items.abc"
dataset.literal(:items__abc___a) #=> "items.abc AS a"
# File lib/sequel/dataset/sql.rb, line 1171
def literal_symbol_append(sql, v)
  c_table, column, c_alias = split_symbol(v)
  if c_table
    quote_identifier_append(sql, c_table)
    sql << DOT
  end
  quote_identifier_append(sql, column)
  as_sql_append(sql, c_alias) if c_alias
end
literal_time(v) click to toggle source

SQL fragment for Time

# File lib/sequel/dataset/sql.rb, line 1182
def literal_time(v)
  format_timestamp(v)
end
literal_true() click to toggle source

SQL fragment for true

# File lib/sequel/dataset/sql.rb, line 1187
def literal_true
  BOOL_TRUE
end
native_function_name(emulated_function) click to toggle source

Get the native function name given the emulated function name.

# File lib/sequel/dataset/sql.rb, line 1192
def native_function_name(emulated_function)
  self.class.const_get(:EMULATED_FUNCTION_MAP).fetch(emulated_function, emulated_function)
end
qualified_column_name(column, table) click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 1198
def qualified_column_name(column, table)
  if Symbol === column 
    c_table, column, _ = split_symbol(column)
    unless c_table
      case table
      when Symbol
        schema, table, t_alias = split_symbol(table)
        t_alias ||= Sequel::SQL::QualifiedIdentifier.new(schema, table) if schema
      when Sequel::SQL::AliasedExpression
        t_alias = table.aliaz
      end
      c_table = t_alias || table
    end
    ::Sequel::SQL::QualifiedIdentifier.new(c_table, column)
  else
    column
  end
end
qualified_expression(e, table) click to toggle source

Qualify the given expression e to the given table.

# File lib/sequel/dataset/sql.rb, line 1218
def qualified_expression(e, table)
  Qualifier.new(self, table).transform(e)
end
select_clause_methods() click to toggle source

The order of methods to call to build the SELECT SQL statement

# File lib/sequel/dataset/sql.rb, line 1223
def select_clause_methods
  SELECT_CLAUSE_METHODS
end
select_columns_sql(sql) click to toggle source

Modify the sql to add the columns selected

# File lib/sequel/dataset/sql.rb, line 1228
def select_columns_sql(sql)
  sql << SPACE
  column_list_append(sql, @opts[:select])
end
select_compounds_sql(sql) click to toggle source

Modify the sql to add a dataset to the via an EXCEPT, INTERSECT, or UNION clause. This uses a subselect for the compound datasets used, because using parantheses doesn't work on all databases. I consider this an ugly hack, but can't I think of a better default.

# File lib/sequel/dataset/sql.rb, line 1248
def select_compounds_sql(sql)
  return unless c = @opts[:compounds]
  c.each do |type, dataset, all|
    sql << SPACE << type.to_s.upcase
    sql << ALL if all
    sql << SPACE
    compound_dataset_sql_append(sql, dataset)
  end
end
select_distinct_sql(sql) click to toggle source

Modify the sql to add the DISTINCT modifier

# File lib/sequel/dataset/sql.rb, line 1234
def select_distinct_sql(sql)
  if distinct = @opts[:distinct]
    sql << DISTINCT
    unless distinct.empty?
      sql << ON_PAREN
      expression_list_append(sql, distinct)
      sql << PAREN_CLOSE
    end
  end
end
select_from_sql(sql) click to toggle source

Modify the sql to add the list of tables to select FROM

# File lib/sequel/dataset/sql.rb, line 1259
def select_from_sql(sql)
  if f = @opts[:from]
    sql << FROM
    source_list_append(sql, f)
  end
end
Also aliased as: delete_from_sql
select_group_sql(sql) click to toggle source

Modify the sql to add the expressions to GROUP BY

# File lib/sequel/dataset/sql.rb, line 1268
def select_group_sql(sql)
  if group = @opts[:group]
    sql << GROUP_BY
    if go = @opts[:group_options]
      if uses_with_rollup?
        expression_list_append(sql, group)
        sql << SPACE_WITH << go.to_s.upcase
      else
        sql << go.to_s.upcase << PAREN_OPEN
        expression_list_append(sql, group)
        sql << PAREN_CLOSE
      end
    else
      expression_list_append(sql, group)
    end
  end
end
select_having_sql(sql) click to toggle source

Modify the sql to add the filter criteria in the HAVING clause

# File lib/sequel/dataset/sql.rb, line 1287
def select_having_sql(sql)
  if having = @opts[:having]
    sql << HAVING
    literal_append(sql, having)
  end
end
select_join_sql(sql) click to toggle source

Modify the sql to add the list of tables to JOIN to

# File lib/sequel/dataset/sql.rb, line 1295
def select_join_sql(sql)
  if js = @opts[:join]
    js.each{|j| literal_append(sql, j)}
  end
end
select_limit_sql(sql) click to toggle source

Modify the sql to limit the number of rows returned and offset

# File lib/sequel/dataset/sql.rb, line 1302
def select_limit_sql(sql)
  if l = @opts[:limit]
    sql << LIMIT
    literal_append(sql, l)
  end
  if o = @opts[:offset]
    sql << OFFSET
    literal_append(sql, o)
  end
end
select_lock_sql(sql) click to toggle source

Modify the sql to support the different types of locking modes.

# File lib/sequel/dataset/sql.rb, line 1314
def select_lock_sql(sql)
  case l = @opts[:lock]
  when :update
    sql << FOR_UPDATE
  when String
    sql << SPACE << l
  end
end
select_order_sql(sql) click to toggle source

Modify the sql to add the expressions to ORDER BY

# File lib/sequel/dataset/sql.rb, line 1324
def select_order_sql(sql)
  if o = @opts[:order]
    sql << ORDER_BY
    expression_list_append(sql, o)
  end
end
select_select_sql(sql) click to toggle source
# File lib/sequel/dataset/sql.rb, line 1333
def select_select_sql(sql)
  sql << SELECT
end
select_where_sql(sql) click to toggle source

Modify the sql to add the filter criteria in the WHERE clause

# File lib/sequel/dataset/sql.rb, line 1338
def select_where_sql(sql)
  if w = @opts[:where]
    sql << WHERE
    literal_append(sql, w)
  end
end
select_with_sql(sql) click to toggle source

SQL Fragment specifying the WITH clause

# File lib/sequel/dataset/sql.rb, line 1348
def select_with_sql(sql)
  ws = opts[:with]
  return if !ws || ws.empty?
  sql << select_with_sql_base
  c = false
  comma = COMMA
  ws.each do |w|
    sql << comma if c
    quote_identifier_append(sql, w[:name])
    if args = w[:args]
     sql << PAREN_OPEN
     identifier_list_append(sql, args)
     sql << PAREN_CLOSE
    end
    sql << AS
    literal_dataset_append(sql, w[:dataset])
    c ||= true
  end
  sql << SPACE
end
select_with_sql_base() click to toggle source

The base keyword to use for the SQL WITH clause

# File lib/sequel/dataset/sql.rb, line 1373
def select_with_sql_base
  SQL_WITH
end
source_list_append(sql, sources) click to toggle source

Converts an array of source names into into a comma separated list.

# File lib/sequel/dataset/sql.rb, line 1378
def source_list_append(sql, sources)
  raise(Error, 'No source specified for query') if sources.nil? || sources == []
  identifier_list_append(sql, sources)
end
split_symbol(sym) click to toggle source

Delegate to Sequel.split_symbol.

# File lib/sequel/dataset/sql.rb, line 1384
def split_symbol(sym)
  Sequel.split_symbol(sym)
end
sql_string_origin() click to toggle source

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

# File lib/sequel/dataset/sql.rb, line 1390
def sql_string_origin
  ''
end
static_sql(sql) click to toggle source

SQL to use if this dataset uses static SQL. Since static SQL can be a PlaceholderLiteralString in addition to a String, we literalize nonstrings.

# File lib/sequel/dataset/sql.rb, line 1397
def static_sql(sql)
  if append_sql = @opts[:append_sql]
    if sql.is_a?(String)
      append_sql << sql
    else
      literal_append(append_sql, sql)
    end
  else
    if sql.is_a?(String)
      sql
    else
      literal(sql)
    end
  end
end
subselect_sql_append(sql, ds) click to toggle source

SQL fragment for a subselect using the given database's SQL.

# File lib/sequel/dataset/sql.rb, line 1414
def subselect_sql_append(sql, ds)
  ds.clone(:append_sql=>sql).sql
end
table_ref_append(sql, v)
Alias for: identifier_append
update_clause_methods() click to toggle source

The order of methods to call to build the UPDATE SQL statement

# File lib/sequel/dataset/sql.rb, line 1419
def update_clause_methods
  UPDATE_CLAUSE_METHODS
end
update_order_sql(sql)
Alias for: select_order_sql
update_returning_sql(sql)
update_set_sql(sql) click to toggle source

The SQL fragment specifying the columns and values to SET.

# File lib/sequel/dataset/sql.rb, line 1432
def update_set_sql(sql)
  values = opts[:values]
  sql << SET
  if values.is_a?(Hash)
    values = opts[:defaults].merge(values) if opts[:defaults]
    values = values.merge(opts[:overrides]) if opts[:overrides]
    c = false
    eq = EQUAL
    values.each do |k, v|
      sql << COMMA if c
      if k.is_a?(String) && !k.is_a?(LiteralString)
        quote_identifier_append(sql, k)
      else
        literal_append(sql, k)
      end
      sql << eq
      literal_append(sql, v)
      c ||= true
    end
  else
    sql << values
  end
end
update_table_sql(sql) click to toggle source

SQL fragment specifying the tables from with to delete. Includes join table if modifying joins is allowed.

# File lib/sequel/dataset/sql.rb, line 1425
def update_table_sql(sql)
  sql << SPACE
  source_list_append(sql, @opts[:from])
  select_join_sql(sql) if supports_modifying_joins?
end
update_update_sql(sql) click to toggle source
# File lib/sequel/dataset/sql.rb, line 1456
def update_update_sql(sql)
  sql << UPDATE
end
update_where_sql(sql)
Alias for: select_where_sql
update_with_sql(sql)
Alias for: select_with_sql