六种删除数据库重复行的方法 .

SQL Server删除重复行是我们最常见的操作之一，下面就为您介绍六种适合不同情况的SQL Server删除重复行的方法，供您参考。

1.如果有ID字段，就是具有唯一性的字段  

delect   table   where   id   not   in   (

select   max(id)   from   table   group   by   col1,col2,col3...
)

group   by   子句后跟的字段就是你用来判断重复的条件，如只有col1，那么只要col1字段内容相同即表示记录相同。  

2. 如果是判断所有字段也可以这样  

select   *   into   #aa   from   table   group   by   id1,id2,....
delete   table
insert   into   table
select   *   from   #aa

3. 没有ID的情况  

select   identity(int,1,1)   as   id,*   into   #temp   from   tabel
delect   #   where   id   not   in   (
select   max(id)   from   #   group   by   col1,col2,col3...)
delect   table
inset   into   table(...)
select   .....   from   #temp

4. col1+','+col2+','...col5 联合主键  

select   *   from     table   where   col1+','+col2+','...col5   in   (
select   max(col1+','+col2+','...col5)   from   table
where   having   count(*)>1
group   by   col1,col2,col3,col4
)

group   by   子句后跟的字段就是你用来判断重复的条件，如只有col1，那么只要col1字段内容相同即表示记录相同。  

5. 

select   identity(int,1,1)   as   id,*   into   #temp   from   tabel
select   *   from     #temp   where   id   in   (
select   max(id)   from   #emp   where   having   count(*)>1   group   by   col1,col2,col3...)

6.

select   distinct   *   into   #temp   from   tablename
delete   tablename
go
insert   tablename   select   *   from   #temp   Sqlclub
go
drop   table   #temp

以上就是SQL Server删除重复行的方法介绍。