SQL删除重复数据只保留一条 .
来源:互联网 发布:怎么看网络是否被劫持 编辑:程序博客网 时间:2024/06/12 23:32
在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢
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 peopleName in (select peopleName from people group by peopleName having count(peopleName) > 1)
and peopleId not in (select min(peopleId) from people group by peopleName having count(peopleName)>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)
6.消除一个字段的左边的第一位:
update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%'
7.消除一个字段的右边的第一位:
update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%村'
8.假删除表中多余的重复记录(多个字段),不包含rowid最小的记录
update vitae set ispass=-1
where peopleId in (select peopleId from vitae group by peopleId
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- SQL删除重复数据只保留一条
- Spring AOP中pointcut expression表达式解析
- 华为官方固件UPDATE.APP解包 编辑 打包详细教程
- TokuDB 引擎安装测试
- JavaScript 模块化编程 - Module Pattern
- 懒加载时为什么不能用self直接访问属性
- SQL删除重复数据只保留一条 .
- LeetCode 419 BattleshipsInABoard DFS、BFS简单的入门
- SpringMVC运行原理
- Spring bean的生命周期init和destory
- 通过样式来去除app的头以及界面全屏(备忘)
- quick-cocos UIInput字数过多崩溃问题
- json和xml传输的区别
- DHCP详解
- 【 第16周项目1-冒泡排序】