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2021-11-13

作者:互联网

解决Oracle删除重复数据只留一条的方法详解
本篇文章是对Oracle删除重复数据只留一条的解决方法,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(Id)来判断select * from 表 where Id in (select Id from 表 group by Id having count(Id) > 1)2、删除表中多余的重复记录,重复记录是根据单个字段(Id)来判断,只留有rowid最小的记录DELETE from 表 WHERE (id) IN ( SELECT id FROM 表 GROUP BY id HAVING COUNT(id) > 1) AND ROWID NOT IN (SELECT MIN(ROWID) FROM 表 GROUP BY id HAVING COUNT() > 1);3、查找表中多余的重复记录(多个字段)select * from 表 awhere (a.Id,a.seq) in (select Id,seq from 表 group by Id,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 表 awhere (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count() > 1)and rowid not in (select min(rowid) from 表 group by Id,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 表 awhere (a.Id,a.seq) in (select Id,seq from 表 group by Id,seq having count() > 1)and rowid not in (select min(rowid) from 表 group by Id,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)方法一复制代码代码如下:declare @max integer,@id integerdeclare cur_rows cursor local for select 主字段,count() from 表名 group by 主字段 having count() >; 1open cur_rowsfetch cur_rows into @id,@maxwhile @@fetch_status=0beginselect @max = @max -1set rowcount @maxdelete from 表名 where 主字段 = @idfetch cur_rows into @id,@maxendclose cur_rowsset rowcount 0 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复制代码代码如下: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复制代码代码如下: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)(四)查询重复复制代码代码如下:select * from tablename where id in (select id from tablenamegroup by idhaving count(id) > 1)您可能感兴趣的文章:oracle查询重复数据和删除重复记录示例分享oracle 删除重复数据Oracle查询表里的重复数据方法

标签:11,13,seq,重复,id,2021,重复记录,Id,select
来源: https://blog.csdn.net/weixin_49913860/article/details/121312104