mysql 删除多余重复记录
（stu表中的名字(name)是重复的）
问题：
在Mysql下执行：
delete from stu where name in (select name from stu group by name having count(name) > 1) and id not in (select id from stu group by name having count(name) > 1);
MySql报错： You can’t specify target table ‘table name’ for update in FROM clause
在 Mysql下执行：
select id from stu where name in (select name from stu group by name having count(name) > 1) and id not in (select id from stu group by name having count(name) > 1);
是成功的。
注意：上面的两句话很矛盾啊。
就现在的mysql版本（我用5.1）来说，不能先select出同一表中的某些值，再update这 个表(在同一语句中)
解决：
create table tmp_table as select id from stu where name in (select name from stu group by name having count(name) > 1) and id not in (select id from stu group by name having count(name) > 1);
delete from stu where id in (select id from tmp_table);
drop table tmp_table;
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