怎样删除重复的行？

蚂蚁的：去除重复值
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


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。

2,
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...)