当我使用 IS NOT NULL 时无法创建 MySQL TRIGGER

CREATE TRIGGER b_I_O AFTER UPDATE ON book
FOR EACH ROW
BEGIN
IF (OLD.status IS NOT NULL AND NEW.status IS NOT NULL AND NEW.status != OLD.status ) THEN
    INSERT INTO book_in_out (astatus, bid, time) VALUES(NEW.status, OLD.id, NOW());
END IF;
END;

经过几个小时的搜索后，第一篇文章在这里。

我尝试在更新预订表后使用触发器插入 book_in_out ，我能够做到这一点，但如果我更新bookName触发器将尝试运行。

我只希望触发器仅在状态列更改时运行。默认值status列是NULL

以下是我不断收到的错误：

#1064 - 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 '' at line 5

你可以尝试这个

delimiter //
CREATE TRIGGER b_I_O AFTER UPDATE ON book
FOR EACH ROW
BEGIN
    IF (OLD.status IS NOT NULL AND NEW.status IS NOT NULL AND NEW.status != OLD.status ) THEN
        INSERT INTO book_in_out (`astatus`, `bid`, `time`) VALUES(NEW.status, OLD.id, NOW());
    END IF;
END;//
delimiter ;