如何正確聲明變量phpmyadmin mysql觸發器？

Question

我有一個數據庫，每當用戶表中的居民地址更新時，我都希望它存儲在用戶的歷史表中。 為此，我正在嘗試編寫觸發器，但是在phpmyadmin中失敗了。 同樣，它也沒有給我適當的理由，所以我可以糾正它。 到目前為止，這是我所做的。

DROP TRIGGER IF EXISTS `record_history`;
CREATE TRIGGER `record_history` AFTER UPDATE ON `s_user` 
FOR EACH ROW
BEGIN
    DECLARE date_current datetime;
    DECLARE residential_address varchar(1000);
    SET @date_current = NOW();
    SET @residential_address = NEW.residential_address;
    IF (@residential_address <> OLD.residential_address AND @residential_address != "" AND @residential_address IS NOT NULL) THEN
        INSERT INTO history_residential_address (`s_u_id`, `residential_address`, `status`, `date_added`, `date_updated`) VALUES 
        (OLD.s_u_id, @residential_address, 1, @date_current, @date_current);
    END IF;
END;
delimiter ;

Answer 1

較干凈的代碼版本

DROP TRIGGER IF EXISTS `record_history`;

delimiter $$
CREATE TRIGGER `record_history` AFTER UPDATE ON `s_user` 
FOR EACH ROW
BEGIN
    IF (new.residential_address <> OLD.residential_address AND new.residential_address <> "" AND new.residential_address IS NOT NULL) THEN
        INSERT INTO history_residential_address (`s_u_id`, `residential_address`, `status`, `date_added`, `date_updated`) VALUES 
        (OLD.s_u_id, new.residential_address, 1, now(), now());
    END IF;
END $$
delimiter ;

如果仍然有問題，請將s_user中的示例數據作為文本添加到問題中。