更新前的MySQL触发器 [英] MySQL trigger before update

问题描述

我想在mysql中添加触发器...

I want to add trigger in mysql ...

CREATE TRIGGER mytrigger BEFORE INSERT ON table_1
FOR EACH ROW
BEGIN SET 
NEW.`order` = (SELECT 1 + COALESCE((SELECT MAX(`order`) FROM `table_1`), 0));
END

我总是会出错:

Error
SQL query: Documentation

CREATE TRIGGER mytrigger BEFORE INSERT ON table_1
FOR EACH
ROW 
BEGIN SET NEW.`order` = ( SELECT 1 + COALESCE( (


SELECT MAX(  `order` ) 
FROM  `table_1` ) , 0 )
);

MySQL said: Documentation

#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 4 

有什么想法吗?

推荐答案

您需要更改定界符.否则，引擎会认为该语句在第一个; 处完成.但这是错误的.

You need to change the delimiter. Otherwise the engine thinks the statement is finished at the first ;. But that would be wrong.

delimiter |
CREATE TRIGGER mytrigger BEFORE INSERT ON table_1
FOR EACH ROW
BEGIN 
  SET NEW.`order` = (SELECT 1 + COALESCE((SELECT MAX(`order`) FROM `table_1`), 0));
END
|
delimiter ;

这篇关于更新前的MySQL触发器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！