首页 / MYSQL / 转sql删除重复记录
转sql删除重复记录
内容导读
互联网集市收集整理的这篇技术教程文章主要介绍了转sql删除重复记录,小编现在分享给大家,供广大互联网技能从业者学习和参考。文章包含4481字,纯文字阅读大概需要7分钟。
内容图文
![转sql删除重复记录](/upload/InfoBanner/zyjiaocheng/566/b5ed2b3c503a4c4a991d440d2571b32f.jpg)
sqlserver 删除 重复 记录 处理(转)发布:mdxy - dxy 字体: [ 增加 减小 ] 类型:转载 删除 重复 记录 有大小关系时,保留大或小其中一个 记录 注:此处 重复 非完全 重复 ,意为某字段数据 重复 HZT表结构 ID int Title nvarchar ( 50 ) AddDate datetime
sqlserver 删除重复记录处理(转) 发布:mdxy-dxy 字体:[增加 减小 ] 类型:转载 删除重复记录有大小关系时,保留大或小其中一个记录 注:此处“重复”非完全重复,意为某字段数据重复 HZT表结构 ID int Title nvarchar(50) AddDate datetime 数据 一. 查找重复记录 1. 查找全部重复记录 Select * From 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1) 2. 过滤重复记录(只显示一条) Select * From HZT Where ID In (Select Max(ID) From HZT Group By Title) 注:此处显示ID最大一条记录 二. 删除重复记录 1. 删除全部重复记录(慎用) Delete 表 Where 重复字段 In (Select 重复字段 From 表 Group By 重复字段 Having Count(*)>1) 2. 保留一条(这个应该是大多数人所需要的) Delete HZT Where ID Not In (Select Max(ID) From HZT Group By Title) 注:此处保留ID最大一条记录 其它相关: 删除重复记录有大小关系时,保留大或小其中一个记录 --> --> (Roy)生成測試數據 if not object_id('Tempdb..#T') is null drop table #T Go Create table #T([ID] int,[Name] nvarchar(1),[Memo] nvarchar(2)) Insert #T select 1,N'A',N'A1' union all select 2,N'A',N'A2' union all select 3,N'A',N'A3' union all select 4,N'B',N'B1' union all select 5,N'B',N'B2' Go --I、Name相同ID最小的记录(推荐用1,2,3),保留最小一条 方法1: delete a from #T a where exists(select 1 from #T where Name=a.Name and ID<a.ID) 方法2: delete a from #T a left join (select min(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID where b.Id is null 方法3: delete a from #T a where ID not in (select min(ID) from #T where Name=a.Name) 方法4(注:ID为唯一时可用): delete a from #T a where ID not in(select min(ID)from #T group by Name) 方法5: delete a from #T a where (select count(1) from #T where Name=a.Name and ID<a.ID)>0 方法6: delete a from #T a where ID<>(select top 1 ID from #T where Name=a.name order by ID) 方法7: delete a from #T a where ID>any(select ID from #T where Name=a.Name) select * from #T 生成结果: /* ID Name Memo ----------- ---- ---- 1 A A1 4 B B1 (2 行受影响) */ --II、Name相同ID保留最大的一条记录: 方法1: delete a from #T a where exists(select 1 from #T where Name=a.Name and ID>a.ID) 方法2: delete a from #T a left join (select max(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID where b.Id is null 方法3: delete a from #T a where ID not in (select max(ID) from #T where Name=a.Name) 方法4(注:ID为唯一时可用): delete a from #T a where ID not in(select max(ID)from #T group by Name) 方法5: delete a from #T a where (select count(1) from #T where Name=a.Name and ID>a.ID)>0 方法6: delete a from #T a where ID<>(select top 1 ID from #T where Name=a.name order by ID desc) 方法7: delete a from #T a where ID(select ID from #T where Name=a.Name) select * from #T /* ID Name Memo ----------- ---- ---- 3 A A3 5 B B2 (2 行受影响) */ --3、删除重复记录没有大小关系时,处理重复值 --> --> (Roy)生成測試數據 if not object_id('Tempdb..#T') is null drop table #T Go Create table #T([Num] int,[Name] nvarchar(1)) Insert #T select 1,N'A' union all select 1,N'A' union all select 1,N'A' union all select 2,N'B' union all select 2,N'B' Go 方法1: if object_id('Tempdb..#') is not null drop table # Select distinct * into # from #T--排除重复记录结果集生成临时表# truncate table #T--清空表 insert #T select * from # --把临时表#插入到表#T中 --查看结果 select * from #T /* Num Name ----------- ---- 1 A 2 B (2 行受影响) */ --重新执行测试数据后用方法2 方法2: alter table #T add ID int identity--新增标识列 go delete a from #T a where exists(select 1 from #T where Num=a.Num and Name=a.Name and ID>a.ID)--只保留一条记录 go alter table #T drop column ID--删除标识列 --查看结果 select * from #T /* Num Name ----------- ---- 1 A 2 B (2 行受影响) */ --重新执行测试数据后用方法3 方法3: declare Roy_Cursor cursor local for select count(1)-1,Num,Name from #T group by Num,Name having count(1)>1 declare @con int,@Num int,@Name nvarchar(1) open Roy_Cursor fetch next from Roy_Cursor into @con,@Num,@Name while @@Fetch_status=0 begin set rowcount @con; delete #T where Num=@Num and Name=@Name set rowcount 0; fetch next from Roy_Cursor into @con,@Num,@Name end close Roy_Cursor deallocate Roy_Cursor --查看结果 select * from #T /* Num Name ----------- ---- 1 A 2 B (2 行受影响) */
内容总结
以上是互联网集市为您收集整理的转sql删除重复记录全部内容,希望文章能够帮你解决转sql删除重复记录所遇到的程序开发问题。 如果觉得互联网集市技术教程内容还不错,欢迎将互联网集市网站推荐给程序员好友。
内容备注
版权声明:本文内容由互联网用户自发贡献,该文观点与技术仅代表作者本人。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容, 请发送邮件至 gblab@vip.qq.com 举报,一经查实,本站将立刻删除。
内容手机端
扫描二维码推送至手机访问。