mysql查重复数据 mysql 如何筛选重复的数据

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.) .

select name, sum(count) as total from table group by name

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

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

在命令行中输入mysql -uroot -p 密码进入mysql.然后输入 show status就可以查看当前mysql数据库的状态.

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

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)

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 用户表 where 用户名 in (select 用户名 from 用户表 group by 用户名 having count(1)>1)

假设表名为test:select * from (select *, concat(name,code) as __f from test order by date desc) __t group by __f;