查询并删除重复记录的SQL语句 查询及删除重复记录的SQL语句 一、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) 二、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 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) 注:rowid为oracle自带不用该..... 三、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) 四、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) 五、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) (二) 比方说 在A表中存在一个字段“name”， 并且不一样记录之间的“name”值有可能会相同， 如今就是须要查询出在该表中的各记录之间，“name”值存在重复的项； Select Name,Count(*) From A Group By Name Having Count(*) > 1 若是还查性别也相同大则以下: Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1 (三) 方法一 declare @max integer,@id integer declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >； 1 open cur_rows fetch cur_rows into @id,@max while @@fetch_status=0 begin select @max = @max -1 set rowcount @max delete from 表名 where 主字段 = @id fetch cur_rows into @id,@max end close cur_rows set rowcount 0 方法二 ＂重复记录＂有两个意义上的重复记录，一是彻底重复的记录，也即全部字段均重复的记录，二是部分关键字段重复的记录，好比Name字段重复，而其余字段不必定重复或都重复能够忽略。 一、对于第一种重复，比较容易解决，使用 select distinct * from tableName 就能够获得无重复记录的结果集。 若是该表须要删除重复的记录（重复记录保留1条），能够按如下方法删除 select distinct * into #Tmp from tableName drop table tableName select * into tableName from #Tmp drop table #Tmp 发生这种重复的缘由是表设计不周产生的，增长惟一索引列便可解决。 二、这类重复问题一般要求保留重复记录中的第一条记录，操做方法以下 假设有重复的字段为Name,Address，要求获得这两个字段惟一的结果集 select identity(int,1,1) as autoID, * into #Tmp from tableName select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID select * from #Tmp where autoID in(select autoID from #tmp2) 最后一个select即获得了Name，Address不重复的结果集（但多了一个autoID字段，实际写时能够写在select子句中省去此列） (四) 查询重复 select * from tablename where id in ( select id from tablename group by id having count(id) > 1 ) [/size]