mysql - 如何创建 BEFORE INSERT 触发器

Question

我正在尝试创建一个 BEFORE INSERT 触发器，但出现了我不明白的错误。

创建触发器的 MySQL 如下所示:

CREATE  TRIGGER `GetPolyLinkID` BEFORE INSERT ON `TableA` 
FOR EACH ROW 
BEGIN
    INSERT INTO TableB () VALUES ();
    NEW.PolyLinkID = last_insert_id();
END

我遇到的错误是

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 'END' at line 1

Answer 1

您忘记了SET ...开始NEW.PolyLinkID = last_insert_id();

还有

要创建复杂的触发器，您必须使用delimiter关键字。

这是 rom https://dev.mysql.com/doc/refman/5.6/en/trigger-syntax.html 中的示例.

delimiter //
CREATE TRIGGER upd_check BEFORE UPDATE ON account
FOR EACH ROW
BEGIN
   IF NEW.amount < 0 THEN
       SET NEW.amount = 0;
   ELSEIF NEW.amount > 100 THEN
        SET NEW.amount = 100;
   END IF;
END;
//
delimiter ;

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