的MySQL创建触发器语法

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 ; 

我努力实现以下目标： 如果有人UPDATE SA值name，在表table_namephone或place（列），并将其值（更新值）NULL那么该值保持旧的（不会更新）。 也许有点短：从不用NULL更新。

上述SQL不会创建触发器，但它不会引发任何错误（phpMyAdmin）。它缺少语法吗？每OLD.column;之后已经尝试过ENDIF; - 没有任何改进。谢谢你的解释。

Answer 1

尝试

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 ;