"“when”子句有什么问题？"

Question

CREATE TRIGGER UPDATE_CAR_DETALS
AFTER UPDATE ON BOOKING_DETALS
FOR EACH ROW
 WHEN (IFNULL(TO_CHAR(NEW.ACT_RET_DT_TIME),NULL) <> 'NULL' OR 
  NEW.BOOKING_STATUS ='C')

Answer 1

触发器中的多语句需要BEGIN和END

此外，当您使用查询选项卡时，您还需要DELIMITER

CASE WHEN 如果你有多种选择，你会使用，但你会更好地使用 IF THEN

DELIMITER $$
CREATE TRIGGER UPDATE_CAR_DETALS 
AFTER UPDATE ON BOOKING_DETALS 
FOR EACH ROW 
BEGIN
    IF (IFNULL(TO_CHAR(NEW.ACT_RET_DT_TIME),NULL) <> 'NULL' OR NEW.BOOKING_STATUS ='C') then 
        BEGIN 
            IF NEW.BOOKING_STATUS ='C' THEN 
                UPDATE CAR SET AVAILABILITY_FLAG = 'A' , LOC_ID = NEW.PICKUP_LOC 
                WHERE REGISTRATION_NUMBER = NEW.REG_NUM; 
            ELSE 
                IF IFNULL(TO_CHAR(NEW.ACT_RET_DT_TIME),NULL) <> NULL THEN 
                
                    UPDATE CAR SET AVAILABILITY_FLAG = 'A' , LOC_ID = NEW.DROP_LOC, MILEAGE = MILEAGE+GET_MILEAGE 
                    WHERE REGISTRATION_NUMBER = NEW.REG_NUM; 
                END IF; 
            END IF; 
        END;
    END IF;
END;
DELIMITER ;