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mysql查重复数据

select sum(数量),名称 from table group by 名称;你按照这个写一下就可以了

如下表:studentid name sex1 zhao man2 qian women3 sun man4 zhao man5 qian women查询 name 列相同的数据:(可能还有其他更简单的方法,暂时只想到这个.) 1.查询数据在哪里重复 SELECT count(name) AS num,name FROM

select userid,username,userlevel from tb where userid not in(select userid from tb group by username,userlevel having count(1)=1)先找出没有重复的userid,然后过滤这些版userid,其余的就是权有重复的了

delete from table a where (a.catid ,a.title ) in (select catid ,title from table group by catid ,title having count(*) > 1) and 自动递增的字段 not in (select min(自动递增的字段) from table group by catid ,title having count(*)>1) and modelid=3

只要能把重复的内容找出来,删除就不是问题了.可以通过select * from dou group by id having count(*) > 1 来完成对重复数据的查找; 之后再delete掉就行了. 下面是我的

楼上正解,mysql的delete in(select)不能在同一个表进行取和删操作,会提示 you can't specify target table 'ttable' for update in from clause 错误,意思是不能对正在打开作为条件的表进行修改所以只好select要保留的数据,插入新表

select * from 表 where n_id in(select s_name from 表 group by s_name,n_money,s_zhipiao,s_date,s_lixi having count(s_name)>1)

操作方法如下:SELECT columname,COUNT(*) AS NUM FROM tablename GROUP BY columname ORDER BY NUM DESC LIMIT 1;

select * from A where A.id=any(select Aid from B)试一下

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