MYSQL中子查询同时执行DELETE或UPDATE操作的简单方法

DELETE FROM `sites_cates` WHERE sid IN (
SELECT `a`.`sid`
FROM `sites_cates` AS a
LEFT JOIN `sites` AS b ON `a`.`site_id` = `b`.`sid`
WHERE `b`.`name` IS NULL
);

这样一条语句会被报错：
#1093 - You can't specify target table 'sites_cates' for update in FROM clause

网上流传最多的解决办法：http://yueliangdao0608.blog.51cto.com/397025/81390

实际上可以更简单：

DELETE FROM `sites_cates` WHERE sid IN (
SELECT `a`.`sid`
FROM (

SELECT *
FROM `sites_cates`
) AS a
LEFT JOIN `sites` AS b ON `a`.`site_id` = `b`.`sid`
WHERE `b`.`name` IS NULL
);