删除sqlserver中的重复记录并按照条件保存其中一条
实施代码如下:
代码如下 | 复制代码 |
SELECT * select distinct tid,* into #aaa from [extract].[dbo].[tbTradeFullinfoGet] delete from [extract].[dbo].[tbTradeFullinfoGet] select a.*, delete from ##test_a alter table ##test_a drop column rows_id drop table [extract].[dbo].[tbTradeFullinfoGet] select * |
代码的功能是删除tbTradeFullinfoGet里重复的记录,且只保存表中intime最大的一条记录!
其它一些删除重复记录sql语句
1、SQL Server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
代码如下 | 复制代码 |
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
代码如下 | 复制代码 |
delete from people where peopleId in (select peopleId from people group by peopleId having count(peopleId) > 1) and rowid not in (select min(rowid) from people group by peopleId having count(peopleId )>1 ) |
3、查找表中多余的重复记录(多个字段)
代码如下 | 复制代码 |
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
代码如下 | 复制代码 |
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、SQL Server查找表中多余的重复记录(多个字段),不包含rowid最小的记录
代码如下 | 复制代码 |
select * from vitae a |
补充一些知识
有两个意义上的重复记录,一是完全重复的记录,也即所有字段均重复的记录,二是部分关键字段重复的记录,比如Name字段重复,而其他字段不一定重复或都重复可以忽略。
1、对于第一种重复,比较容易解决,使用
代码如下 | 复制代码 |
select distinct * from tableName |
就可以得到无重复记录的结果集。
如果该表需要删除重复的记录(重复记录保留1条),可以按以下方法删除
代码如下 | 复制代码 |
select distinct * into #Tmp from tableName drop table tableName select * into tableName from #Tmp drop table #Tmp |
发生这种重复的原因是表设计不周产生的,增加唯一索引列即可解决。
2、这类重复问题通常要求保留重复记录中的第一条记录,操作方法如下
假设有重复的字段为Name,Address,要求得到这两个字段唯一的结果集
代码如下 | 复制代码 |
select identity(int,1,1) as autoID, * into #Tmp from tableName select min(autoID) as autoID into #Tmp2 from #Tmp group by Name,autoID select * from #Tmp where autoID in(select autoID from #tmp2) |
最后一个select即得到了Name,Address不重复的结果集(但多了一个autoID字段,实际写时可以写在select子句中省去此列)
3、部分关键字段重复,且记录中有ID.
第一种方法可一次删除所有重复的..(只保留重复中ID最小的记录)。
代码如下 | 复制代码 |
delete from table where id not in ( select min(id) from table group by name) |
第二种方法每次只删除重复中ID最大的一条记录。
代码如下 | 复制代码 |
delete from table where id in ( select max(id) from table group by name having count(*)>1) |
补充:数据库,Mssql