Class: Sequel::SQL::OrderedExpression

Inherits:
Expression show all
Defined in:
lib/sequel/sql.rb

Overview

Represents a column/expression to order the result set by.

Constant Summary collapse

INVERT_NULLS = 
{:first=>:last, :last=>:first}.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods inherited from Expression

#==, attr_reader, comparison_attrs, #eql?, #hash, #inspect, #lit, #sql_literal

Constructor Details

#initialize(expression, descending = true, opts = {}) ⇒ OrderedExpression

Set the expression and descending attributes to the given values. Options:

:nulls

Can be :first/:last for NULLS FIRST/LAST.



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# File 'lib/sequel/sql.rb', line 910

def initialize(expression, descending = true, opts={})
  @expression, @descending, @nulls = expression, descending, opts[:nulls]
end

Instance Attribute Details

#descending ⇒ Object (readonly)

Whether the expression should order the result set in a descending manner



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# File 'lib/sequel/sql.rb', line 901

def descending
  @descending
end

#expression ⇒ Object (readonly)

The expression to order the result set by.



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# File 'lib/sequel/sql.rb', line 898

def expression
  @expression
end

#nulls ⇒ Object (readonly)

Whether to sort NULLS FIRST/LAST



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# File 'lib/sequel/sql.rb', line 904

def nulls
  @nulls
end

Instance Method Details

#asc ⇒ Object

Return a copy that is ordered ASC



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# File 'lib/sequel/sql.rb', line 915

def asc
  OrderedExpression.new(@expression, false, :nulls=>@nulls)
end

#desc ⇒ Object

Return a copy that is ordered DESC



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# File 'lib/sequel/sql.rb', line 920

def desc
  OrderedExpression.new(@expression, true, :nulls=>@nulls)
end

#invert ⇒ Object

Return an inverted expression, changing ASC to DESC and NULLS FIRST to NULLS LAST.



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# File 'lib/sequel/sql.rb', line 925

def invert
  OrderedExpression.new(@expression, !@descending, :nulls=>INVERT_NULLS.fetch(@nulls, @nulls))
end