去除表中重复数据的方法

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

col1+','+col2+','...col5 联合主键

alter table 表 add  newfield int identity(1,1)

delete 表
where newfield not in(
 select min(newfield) from 表 group by 除newfield外的所有字段
                     )

alter table 表 drop column newfield

4,
select distinct * into #t from tablename

truncate table tablename

insert  tablename  select * from #t

drop table #t