MySQL觸發器 - 僅當數據不同時才插入另一個表中

Question

僅當數據不同時，纔想將數據插入另一個表中。
所以爲了這個，我創建了第一個表的觸發器，像這樣：

CREATE TRIGGER `RegistrationHistory` AFTER UPDATE ON `registration` 
FOR EACH ROW 
INSERT INTO registration_history (`Key`, `Name`, `Version`, `LastUpdate`) 
SELECT OLD.Key, OLD.Name, OLD.Version, NOW() 
WHERE OLD.Key != NEW.Key 
AND OLD.Name != NEW.Name 
AND OLD.Version != NEW.Version 

的問題是，它的錯誤了與：

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE OLD.Key != NEW.Key

我注意到，如果我嘗試這不工作要麼：

SELECT 'ACBDE' 
WHERE 1 = 1 

那麼我應該如何插入歷史表使用MySQL只有當有差異？在if語句

Answer 1

嘗試包裝：

CREATE TRIGGER `RegistrationHistory` AFTER UPDATE ON `registration` 
FOR EACH ROW BEGIN 
    IF (NEW.Key != OLD.Key AND NEW.Name != OLD.Name AND NEW.Version != OLD.Version) Then 
    INSERT INTO registration_history (`Key`, `Name`, `Version`, `LastUpdate`) 
     VALUES(NEW.Key, NEW.Name, NEW.Version, NOW()); 
    END IF; 
END