SQL查找 删除重复数据只保留一条
2013-08-12 16:11
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--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 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 delete from people where 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 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 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 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) --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=-1 where peopleId in (select peopleId from vitae group by peopleId
-- 更新时间 某日期以后随机 select dateadd(ss, abs(checksum(newid()) % 31449600),'2014-01-01 ' + CONVERT (VARCHAR, getdate(), 14))
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