的MySQL創建觸發器語法

Question

DELIMITER // 
CREATE TRIGGER never_update_with_null 
BEFORE UPDATE 
ON `table_name` 
FOR EACH ROW 
BEGIN 
    IF OLD.name IS NOT NULL AND NEW.name IS NULL THEN 
     SET NEW.name = OLD.name; 
    IF OLD.phone IS NOT NULL AND NEW.name IS NULL THEN 
     SET NEW.phone = OLD.phone; 
    IF OLD.place IS NOT NULL AND NEW.place IS NULL THEN 
     SET NEW.place = OLD.place; 
END; // 
DELIMITER ; 

我努力實現以下目標： 如果有人UPDATE SA值name，在表table_namephone或place（列），並將其值（更新值）NULL那麼該值保持舊的（不會更新）。 也許有點短：從不用NULL更新。

上述SQL不會創建觸發器，但它不會引發任何錯誤（phpMyAdmin）。它缺少語法嗎？每OLD.column;之後已經嘗試過ENDIF; - 沒有任何改進。謝謝你的解釋。

Answer 1

嘗試

DELIMITER // 
CREATE TRIGGER never_update_with_null 
BEFORE UPDATE 
ON `table_name` 
FOR EACH ROW 
BEGIN 
    IF OLD.name IS NOT NULL AND NEW.name IS NULL THEN 
     SET NEW.name = OLD.name; 
    END IF; 
    IF OLD.phone IS NOT NULL AND NEW.phone IS NULL THEN 
     SET NEW.phone = OLD.phone; 
    END IF; 
    IF OLD.place IS NOT NULL AND NEW.place IS NULL THEN 
     SET NEW.place = OLD.place; 
    END IF; 
END; // 
DELIMITER ;