mysql 查询语句如何去重复

在用select语句查询mysql数据库的时候，你可以加上distinct修饰符，这样就可以去掉好多重复的，比如

SELECT

distinct(`lcontent`)

FROM

`caiji_ym_liuyan`

当然实际情况中的重复问题还有很多，需要自己的实际情况，构造相应的select语句。

select distinct biao.id

from biao

left outer join (select col1, col2

from biao

group by col1, col2

having count(*) >1) tmp

on biao.col1 = tmp.col1

and biao.col2 = tmp.col2

你是要查找数据库中某个字段下的相同数据吧，我给你写2个例子

(数据库执行效率高)

select * from dbo.MediafileInfo as a where

(VideoDownUrl IN (SELECT VideoDownUrl FROM MediafileInfo AS B WHERE A.ProgramID <>B.ProgramID))

(数据库执行效率低)

SELECT *

FROM MediafileInfo AS A

WHERE (SELECT COUNT(*) FROM MediafileInfo WHERE VideoDownUrl=A.VideoDownUrl)>1

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