MySQL 删除 with where 不会报错

Question

我有一个这样的表:

create table person (
  id integer,
  Email varchar(100)
);


insert into person values (1, 'john@example.com');
insert into person values (2, 'bob@example.com');
insert into person values (3, 'john@example.com');
insert into person values (4, 'john@example.com');

现在，我需要删除重复行并保留最小 Id，这意味着删除后表将是:

+----+------------------+
| Id | Email            |
+----+------------------+
| 1  | john@example.com |
| 2  | bob@example.com  |
+----+------------------+

我得到这个是为了获取一个不重复的 id 列表:

select Id from Person group by Email;

删除代码是:

delete from Person
  where Person.Id not in 
    (select Id from Person group by Email);

但对我来说不起作用，为什么我不能这样写以及如何解决它？

Answer 1

您可以使用 JOIN as 轻松完成

delete p from person p 
join ( 
  select min(id) as id ,email from person group by email 
)p1 
on p1.id < p.id and p1.Email = p.Email ;