我们经常遇到SQL Server数据重复的问题，和大家分享一下如何删除SQL Server重复数据,SQL Server重复数据有两个意义上的重复记录，一是完全重复的记录，即所有字段均重复的记录，二是部分关键字段重复的记录，比如Name字段重复，而其他字段不一定重复或都重复可以忽略。1、对于第一种重复，比较容易解决，使用select distinct * from tableName 就可以得到无重复记录的结果集。如果该表需要删除重复的记录(重复记录保留1条)，可以按以下方法删除。select distinct * into #Tmp from tableNamedrop table tableNameselect * into tableName from #Tmpdrop table #Tmp发生这种重复的原因是表设计不周产生的，增加唯一索引列即可解决。2、这类重复问题通常要求保留重复记录中的第一条记录，操作方法如下。假设有重复的字段为Name，Address，要求得到这两个字段唯一的结果集。select identity(int,1,1) as autoID, * into #Tmp from tableNameselect min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoIDselect * from #Tmp where autoID in(select autoID from #tmp2)最后一个select即得到了Name，Address不重复的结果集(但多了一个autoID字段，实际写时可以写在select子句中省去此列)。
from tablaA a
where exists (
select * from tableB b
where a.ID1=b.ID1 and a.ID2=b.ID2 .....--重复字段
and a.col1 > b.col1 --条件筛选字段
)
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,seq having count(*) > 1) and seq in （select 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)
delete table bb