MySQL : You can't specify target table 'Person' for update in FROM clause

Posted 2021-05-29 木析

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    
)  ;