Method: Sequel::MSSQL::EmulateLateralWithApply#from

Defined in:
lib/sequel/extensions/mssql_emulate_lateral_with_apply.rb

#from(*source, &block) ⇒ Object

When a FROM entry uses a LATERAL subquery, convert that entry into a CROSS APPLY.



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# File 'lib/sequel/extensions/mssql_emulate_lateral_with_apply.rb', line 58

def from(*source, &block)
  virtual_row_columns(source, block)
  lateral, source = source.partition{|t| t.is_a?(Sequel::Dataset) && t.opts[:lateral] || (t.is_a?(Sequel::SQL::AliasedExpression) && t.expression.is_a?(Sequel::Dataset) && t.expression.opts[:lateral])} unless source.empty?
  return super(*source, &nil) if !lateral || lateral.empty?

  ds = from(*source)
  lateral.each do |l|
    l = if l.is_a?(Sequel::SQL::AliasedExpression)
      l.expression.clone(:lateral=>nil).as(l.alias)
    else
      l.clone(:lateral=>nil)
    end
    ds = ds.cross_apply(l)
  end
  ds
end