内容来源于:http://blog.csdn.net/anya/article/details/6407280
用SQL语句,删除掉重复项只保留一条
在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢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select * from peoplewhere 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delete from peoplewhere peopleName in (select peopleName from people group by peopleName having count(peopleName) > 1)and peopleId not in (select min(peopleId) from people group by peopleName having count(peopleName)>1)3、查找表中多余的重复记录（多个字段）select * from vitae awhere (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delete from vitae awhere (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select * from vitae awhere (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) 6.消除一个字段的左边的第一位：update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%'7.消除一个字段的右边的第一位：update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%村'8.假删除表中多余的重复记录（多个字段），不包含rowid最小的记录update vitae set ispass=-1where peopleId in (select peopleId from vitae group by peopleId