CREATE TRIGGER TRI_JPNO FOR IPGO BEFORE INSERT POSITION 0
AS
  DECLARE VARIABLE MAX_NUM INTEGER;
BEGIN
  SELECT MAX(JPNO) FROM IPGO WHERE (IDATE=NEW.IDATE)
                   INTO :MAX_NUM;
  IF (MAX_NUM IS NULL) THEN MAX_NUM=1;
  ELSE MAX_NUM=MAX_NUM+1;
  NEW.JPNO=MAX_NUM;
END

라구 하니 되는군여
답변주신 님 감사하구여 겨울내 감기 조심하시구 행복하십시요 ^^*