你真的会玩SQL吗？删除重复数据且只保留一条

 --查询出所有重复数据,并给定递增id
 SELECT IDENTITY( INT,1,1 ) AS id ,
        mac ,
        content 
 INTO   #tmp
 FROM   TB_MACVideoAndPicture
 WHERE  mac IN ( SELECT    mac
                  FROM      TB_MACVideoAndPicture
                  GROUP BY  mac ,content
                  HAVING    COUNT(*) > 1 )
 ORDER BY mac ,content
 
 
 --删除原表中所有重复数据
 DELETE FROM TB_MACVideoAndPicture
 WHERE  mac IN ( SELECT  mac FROM  #tmp )
 
 --插入id最小的重复数据到原表
 INSERT INTO TB_MACVideoAndPicture
        SELECT  UPPER(mac) mac ,
                content 
        FROM    #tmp a
        WHERE   id IN ( SELECT  MIN(id)
                        FROM    #tmp b
                        WHERE   a.mac = b.mac AND a.content = b.content
                        GROUP BY mac ,content )
 

 DROP TABLE #tmp