CREATE TRIGGER trg_Documents_Valid_Period BEFORE INSERT, UPDATE, DELETE
ORDER  1  ON documents
REFERENCING OLD AS OldValue NEW AS NewValue
BEGIN
  DECLARE @date_period date;

  IF INSERTING
  THEN
    SET @date_period = NewValue.date_period;
  ELSE
    SET @date_period = OldValue.date_period;
  END IF;

  IF EXISTS(
    SELECT *
    FROM periods
    WHERE (@date_period BETWEEN nd AND kd) AND status = 'Закрыт' )
  THEN
    RAISERROR  20000  'Ай-я-я-й';
    RETURN;
  END IF;
END;

[Sybase][ODBC Driver][Adaptive Server Anywhere]Column 'date_period' not found
SQLCODE: - 143 
SQLSTATE: 42S22

ALTER TRIGGER "TR_DOC_PP_period" BEFORE INSERT, DELETE, UPDATE
ORDER  1  ON "ADS"."DOC_PP"
REFERENCING OLD AS old_tab NEW AS new_tab
FOR EACH ROW /* WHEN( search_condition ) */
BEGIN
  DECLARE @date_period date;

  IF INSERTING
  THEN
    SET @date_period = new_tab.date_period;
  ELSE
    SET @date_period = old_tab.date_period;
  END IF;

  IF EXISTS(
    SELECT *
    FROM SP_PRD --Справочник периодов
    WHERE (@date_period BETWEEN N_PRD AND K_PRD) AND status = 'Закрыт' )
  THEN
    RAISERROR  20000  'Ай-я-я-й';
    RETURN;
  END IF;

END