大家都知道用group by的话，select 后面指定的字段必须与group by后面的一致。group by 只有个别字段，如果拿出其他未分组的字段信息呢？在网上搜了下，
总结如下：
使用了group by 之后，就要求select后面的字段包含在group by 或聚合函数里面，这时如果想读取其它字段则无法实现。
将你需要的字段放进max或min函数中，max:支持字符类型、数字类型。
select
max(id) as id,username,password from users
group by username,password
order by id desc
或者用:
select * from
(select part from employee group by part) as t1
inner join
(select distinct englishname from employee where part in (select part from employee group by part )) as t2
on t1.part =t2.part
参考：
select v.p ,v.a,v.b,v.c,v.d,v.e,v.f,v.g,v.h,v.i,v.j,v.k,v.l,v.m,v.m,v.n,v.o from vegaga v right join (
select min(id) as id,a,b,c,d,e,f,g,h,n from vegaga where a is not null group by a,b,c,d,e,f,g,h,n
) as v1 on v1.id=v.id order by v.id
我在sqlserver中这样写，达到了我想要的效果。
select max(CrmMemberID) as CrmMemberID,MemberName,COUNT("MemberName") as count_name
from [zfnewdb].[dbo].[tblCrmMemberAssign]
group by MemberName
having COUNT("MemberName") = 1
不仅拿到了MemberName字段，还拿到了我想要的CrmMemberID字段。想要其它字段继续像上面的CrmMemberID字段那样加上就行了。