# File lib/arel/engines/sql/formatters.rb, line 35
      def expression(expression)
        if expression.function_sql == "DISTINCT"
          "#{expression.function_sql} #{expression.attribute.to_sql(self)}" +
          (expression.alias ? " AS #{quote_column_name(expression.alias)}" : '')
        else
          "#{expression.function_sql}(#{expression.attribute.to_sql(self)})" +
          (expression.alias ? " AS #{quote_column_name(expression.alias)}" : " AS #{expression.function_sql.to_s.downcase}_id")
        end
      end