手机
当前位置:查字典教程网 >编程开发 >mssql数据库 >SQL删除重复数据只保留一条
SQL删除重复数据只保留一条
摘要:用SQL语句,删除掉重复项只保留一条在几千条记录里,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...

用SQL语句,删除掉重复项只保留一条

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】相关文章:

SQL 研究 相似的数据类型

SQL命令大全-中英文对照第1/3页

SQL SERVER数据库开发之存储过程应用

SQL语句技巧:按月统计数据

SQL server 管理事务和数据库介绍

SQL查看表中重复数据

SQL2000中改名和删除默认sa帐号的最安全方法

收缩后对数据库的使用有影响吗?

删除SQL数据库中事务日志方法

海量数据库的查询优化及分页算法方案

精品推荐
分类导航