SQL删除重复数据只保留一条
来源:互联网 发布:淘宝店铺名称可以改吗 编辑:程序博客网 时间:2024/05/23 11:47
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
- 读写ini文件
- 如何学习技术?
- 浅谈Iframe和FRAME的区别
- 多线程开发之NSOperation与NSThread
- MFC模板、文档、视图、框架的关系
- SQL删除重复数据只保留一条
- 明天就要离开了
- TCHAR、wchar_t、char及字符串处理函数区别
- 情感的旅途
- Java位移运算符的原理和作用
- Java程序员成长之路(你必须知道的技术点)
- 第四周上机--任务四--设计一个工资类(Salary)--完成各个功能--文件中读入数据--学会ASCII文件的操作
- SQL多表连接查询与集合的并、交、差运算查询
- 什么是安规电容及 XI X2 X3 Y1 Y2 Y3 Y4