1、查询表中反复数据。select
* from people
 where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1)
2、删除表中多余的反复记录，反复记录是依据单个字段（peopleId）来推断。仅仅留有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)
3、查找表中多余的反复记录（多个字段）
elect * from vitae a
where (a.peopleId,a.seq) in (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
4、删除表中多余的反复记录（多个字段），仅仅留有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、查找表中多余的反复记录（多个字段）。不包括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)
例如说
在A表中存在一个字段“name”，
并且不同记录之间的“name”值有可能会同样，
如今就是须要查询出在该表中的各记录之间，“name”值存在反复的项；
Select Name,Count(*) From A Group By Name Having Count(*) > 1
假设还查性别也同样大则例如以下:
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
＂反复记录＂有两个意义上的反复记录，一是全然反复的记录，也即全部字段均反复的记录，二是部分keyword段反复的记录。比方Name字段反复，而其它字段不一定反复或都反复能够忽略。
1、对于第一种反复，比較easy解决。使用
select distinct * from tableName
就能够得到无反复记录的结果集。
假设该表须要删除反复的记录（反复记录保留1条）。能够按下面方法删除
select distinct * into #Tmp from tableName
drop table tableName
select * into tableName from #Tmp
drop table #Tmp
发生这样的反复的原因是表 设计不周产生的，添加唯一索引列就可以解决。
2、这类反复问题通常要求保留反复记录中的第一条记录，操作方法例如以下
如果有反复的字段为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 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即得到了Name，Address不反复的结果集（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)
查询反复
select * from tablename where id in (select id from tablename group by id
having count(id) > 1）
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