无法创建MySql触发器

Question

我是MySql触发器的新手。我有一个任务是创建触发器，检查插入值，但它在if语句中抛出了一个错误，我不知道如何解决它

    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 'IF  new.price > @maxi 
        THEN
            ROLLBACK
        else
            INSERT INTO Laptop
            SELECT * FROM inserted
 at line 1

代码：

    CREATE TRIGGER ChekInsert BEFORE INSERT ON Laptop FOR EACH ROW
    BEGIN

        SELECT @maxi := MAX(price)*0.5 FROM Laptop
        IF  new.price > @maxi 
        THEN
            ROLLBACK
        else
            INSERT INTO Laptop
            SELECT * FROM inserted
        end if
    END    

Answer 1

更改了我的代码，一切都正常

delimiter $$
CREATE TRIGGER ChekInsert BEFORE INSERT ON Laptop FOR EACH ROW
BEGIN
    declare maxi float;
    select MAX(price)*0.5 into maxi FROM Laptop;
        if NEW.price > @maxi then
            SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'price is incorrect';
        end if;

end $$

delimiter;

要在触发器中包含多个语句，您必须更改缺省分隔符，并且不需要rollback，因为在抛出错误时它是触发器