SQL删除重复数据只保留一条
来源:互联网 发布:怎样应对网络安全问题 编辑:程序博客网 时间:2024/05/18 17:24
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
- Matlab入门二(数据保存)
- java File类了解
- 都是空格惹的祸
- 机房收费系统合作版(一)——框架搭建
- 【Hdu】Minimum Inversion Number(逆序,线段树)
- SQL删除重复数据只保留一条
- java IO字节流
- Mac OS使用技巧之十:Finder的详细使用方法
- 银行卡安全密码算法辅助计算工具(3DES+RSA)
- Example 2.2 倒蛇阵填数
- tcp服务器编程
- kbengine下载
- Linux网络编程:原始套接字编程(上)
- iptables