为什么以下查询不起作用您不能在FROM子句中指定目标表'p1'进行更新？

问题描述

delete from Person p1 
where p1.id NOT IN (
    select * 
    from (select min(id) from Person p2 where p2.Email=p1.Email) p
);

此查询有效，但如果我删除select *，它会说（您无法在FROM子句中指定目标表'p1'用于更新。为什么会这样？

delete from Person p1 
where p1.id NOT IN (select min(id) from Person p2 where p2.Email=p1.Email);

解决方法

MySQL不支持在WHERE子句中重新打开DML语句的目标表。您可以使用join来代替嵌套选择，这可以使代码更简洁：

delete p1
from person p1 
inner join (select email,min(id) min_id from person group by email) p2
    on p1.email = p2.email and p1.id > p2.min_id