def sql_for_tt_booking_fixed_version_field(field, operator, value)
    if operator == "="
      "( #{Issue.table_name}.fixed_version_id IN (" + value.collect { |val| "'#{self.class.connection.quote_string(val)}'" }.join(",") + ") )"
    else
      "( #{Issue.table_name}.fixed_version_id NOT IN (" + value.collect { |val| "'#{self.class.connection.quote_string(val)}'" }.join(",") + ") OR #{Issue.table_name}.fixed_version_id IS NULL )"