原因：mysql不能在同一语句中先select出同一表中的某些值，再对这个表做修改
解决方法：添加临时表
参考：https://blog.csdn.net/baidu456356/article/details/101603359
DELETE FROM Person WHERE Id NOT IN (
--mysql不能先select出同一表中的某些值，再update这个表(在同一语句中)
SELECT MIN(p.Id) AS Id
FROM Person p
GROUP BY p.Email
) ;
DELETE FROM Person WHERE Id NOT IN (
--把临时表再select以下就好了
SELECT Id FROM (
SELECT MIN(p.Id) AS Id
FROM Person p
GROUP BY p.Email) temp
) ;
MySQL : You can't specify target table 'Person' for update in FROM clause
原文：https://www.cnblogs.com/forest-stream/p/14823495.html