CREATE OR REPLACE TRIGGER LOG_RESERVATION_TRG
  BEFORE INSERT OR UPDATE ON RESERVATIONS
  FOR EACH ROW
  BEGIN
    INSERT INTO RESERVATION_HISTORY(ROOM_CODE, USER_ID, DATE_FROM, DATE_TO, INSERTING_USER_ID, INSERT_DATE)
    VALUES (:NEW.ROOM_CODE, :NEW.USER_ID, :NEW.DATE_FROM, :NEW.DATE_TO, USER, SYSDATE);
  END;