select * from t aa
where createtime=(select top 1 createtime from t where projectname=aa.projectname
order by createtime desc)
where createtime=(select top 1 createtime from t where projectname=aa.projectname
order by createtime desc)
from t,(select projectname,createtime=max(createtime) from t group by projectname) a
where t.projectname=a.projectname and t.createtime=a.createtime
--你给的结果不对
from t
group by projectname) b
where a.projectname=b.projectname and a.createtime=b.createtime
(select projectname,content,createtime=min(createtime) from tb group by rojectname,content)b
where a.projectname=b.projectname and a.content=b.content and a.createtime=b.createtime
select *
from t a
where createtime=(select top 1 createtime from t where projectname=a.projectname
order by createtime desc)
where createtime=(select top 1 createtime from t where projectname=a.projectname
order by createtime desc)
on a.projectname=b.projectname and a.createtime=b.createtime
select id, projectname,content,createtime from t where id in (select max(id) from t group by projectname)