SQL 查询重复数据并显示重复次数

查询有重复数据的记录
select * from F group by a,b,c,d having count(*)>1

删除重复一模一样的记录，只保留一条记录

<span style="font-family:Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;line-height: 18px;">select distinct * into #Tmp from tableName</span><br style="line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;" /><span style="font-family:Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;line-height: 18px;">drop table tableName</span><br style="line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;" /><span style="font-family:Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;line-height: 18px;">select * into tableName from #Tmp</span><br style="line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;" /><span style="font-family:Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;line-height: 18px;">drop table #Tmp</span>

<h2 style="margin: 0px; color: rgb(68, 68, 68); font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif; font-size: 12px;"><a target=_blank class="singleposttitle" id="cb_post_title_url" style="color: rgb(34, 51, 85);" href="http://www.cnblogs.com/sunxiaonan/archive/2009/11/24/1609439.html" target="_blank">SQL删除重复数据方法</a></h2>

<p style="margin: 10px auto; line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;">例如： 
id           name         value 
1               a                 pp 
2               a                 pp 
3               b                 iii 
4               b                 pp 
5               b                 pp 
6               c                 pp 
7               c                 pp 
8               c                 iii 
id是主键 
要求得到这样的结果 
id           name         value 
1               a                 pp 
3               b                 iii 
4               b                 pp 
6               c                 pp 
8               c                 iii</p><p style="margin: 10px auto; line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;">方法1
delete   YourTable   
where   [id]   not   in   ( 
select   max([id])   from   YourTable   
group   by   (name   +   value)) 

方法2
delete   a 
from   表   a   left   join( 
select   id=min(id)   from   表   group   by   name,value 
)b   on   a.id=b.id 
where   b.id   is   null 



查询及删除重复记录的SQL语句
查询及删除重复记录的SQL语句
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 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)</p><p style="margin: 10px auto; line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;">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)
(二)
比方说
在A表中存在一个字段“name”，
而且不同记录之间的“name”值有可能会相同，
现在就是需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
如果还查性别也相同大则如下:
Select Name,sex,Count(*) From A Group By Name,sex Having Count(*) > 1</p><p style="margin: 10px auto; line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;">(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</p><p style="margin: 10px auto; line-height: 18px; font-family: Verdana,"Lucida Grande",Arial,Helvetica,sans-serif;">方法二
＂重复记录＂有两个意义上的重复记录，一是完全重复的记录，也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 tableName
drop table tableName
select * into tableName from #Tmp
drop 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 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）
(四)
查询重复
select * from tablename where id in (
select id from tablename
group by id
having count(id) > 1
)</p>