mysql 查找出重复数据 然后把删除重复的数据 保留一条 delete from temp where id in (select id from (select max(id) as id,count(url) as count from temp group by url having count 1 order by count desc) as tab ) 如何去掉数据库重复记录并且只保留
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mysql 查找出重复数据 然后把删除重复的数据 保留一条 delete from temp where id in (select id from (select max(id) as id,count(url) as count from temp group by url having count >1 order by count desc) as tab ) 如何去掉数据库重复记录并且只保留一条记录 在n条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复并保留一条呢？方法如下： 1、查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断 [sql] view plaincopy select * from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1) 2、删除表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断，只留有rowid最小的记录 [sql] view plaincopy delete from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1) and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1) 3、查找表中多余的重复记录（多个字段） [sql] view plaincopy select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1) 4、删除表中多余的重复记录（多个字段），只留有rowid最小的记录 [sql] view plaincopy delete from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1) and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1) 5、查找表中多余的重复记录（多个字段），不包含rowid最小的记录 [sql] view plaincopy select * from vitae a where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1) and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1) |
