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SQL重复记录查询
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)
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
(三)
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]方法一
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]declare @max integer,@id integer
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]declare cur_rows cursor local for select 主字段,count(*) from 表名 group by 主字段 having count(*) >； 1
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]open cur_rows
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]fetch cur_rows into @id,@max
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]while @@fetch_status=0
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]begin
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select @max = @max -1
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]set rowcount @max
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]delete from 表名 where 主字段 = @id
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]fetch cur_rows into @id,@max
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]end
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]close cur_rows
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]set rowcount 0
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 方法二
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 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。
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 1、对于第一种重复，比较容易解决，使用
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select distinct * from tableName
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 就可以得到无重复记录的结果集。
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 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
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select distinct * into #Tmp from tableName
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]drop table tableName
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select * into tableName from #Tmp
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]drop table #Tmp
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 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。
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 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
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 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
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select identity(int,1,1) as autoID, * into #Tmp from tableName
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select * from #Tmp where autoID in(select autoID from #tmp2)
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img] 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）
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img](四)[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]查询重复
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select * from tablename where id in (
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]select id from tablename
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]group by id
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img]having count(id) > 1
[img]http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif[/img])
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