也是有两种解法

sql
create table Person(
    id int primary key,
    email varchar(20)
) ;

show tables;



drop table Person;

insert into Person values 
(1,'join@qq.com'),(2,'join@qq.com'),(3,'qwm@qq.com');

delete p1 from Person as p1,
Person p2 where p1.email = p2.email 
and p1.id > p2.id;

delete from Person where
id not in (select id from
(select min(id) as id from Person group by email) t);

总结

• 不能对表同时间删除和查询
• group by 语句可以按字段分组