create table student2(id int auto_increment primary key,code varchar(20),name varchar(20));insert into student2 values(null,'','张三'),(null,'','李四'),(null,'','张三');

//如下语句， mysql 报告错误， 可能删除依赖后面统计语句， 而删除又导致统计语句结果不

一致。

delete from student2 where id not in(select min(id) from student2 group by name);

//但是， 如下语句没有问题：

select * from student2 where id not in(select min(id) from student2 group by name);

//于是， 我想先把分组的结果做成虚表， 然后从虚表中选出结果， 最后再将结果作为删除的

条件数据。

delete from student2 where id not in(select mid from (select min(id) mid

from student2 group by name) as t);

或者：

delete from student2 where id not in
(select min(id) from 
(

select * from student2) as t group by t.name);