Sql server 最大列概念。。。sql server

我有以下疑问-

select System_Id, TeamProjectSK, System_State, System_Rev
from
(
select w1.System_Id, w1.TeamProjectSK, w1.System_State, w1.System_Rev,
row_number() over(partition by w1.System_Id, w1.TeamProjectSK, w1.System_State order by w1.System_Rev desc) rn
from dbo.DimWorkItem w1  
where w1.System_Id = 1691  
) d
where rn = 1
order by System_Id, TeamProjectSK,System_Rev desc;

输出看起来像-

System_Id    TeamProjectSK  System_State    System_Rev
1691     126              Closed              17
1691     126              Resolved            14
1691     126              Active              13
1691     126              Proposed            2

但是我希望我的输出选择具有最高“System\u Rev”值的行&它应该如下所示-

System_Id    TeamProjectSK  System_State    System_Rev
1691         126              Closed              17

现在，我尝试使用下面的查询重新使用“max”概念。但这对我的帮助不起作用。请让我知道您的意见，或者是否有更好的方法获得相同的结果

select System_Id, TeamProjectSK, System_State, max(System_Rev)
from
(select System_Id, TeamProjectSK, System_State, System_Rev
from
(
    select w1.System_Id, w1.TeamProjectSK, w1.System_State, w1.System_Rev,
        row_number() over(partition by w1.System_Id, w1.TeamProjectSK, w1.System_State order by w1.System_Rev desc) rn
    from dbo.DimWorkItem w1  
    where w1.System_Id = 1691  
) d
where rn = 1
) e
group by System_Id, TeamProjectSK, System_State
having max(System_Rev)>1

---

如果您只想返回带有max

System\u Rev

的行，则需要将

row\u number（）

更改为仅按

System\u id

和

TeamProjectSK

进行分区。通过

System\u State

删除分区

select System_Id, TeamProjectSK, System_State, System_Rev
from
(
    select w1.System_Id, w1.TeamProjectSK, w1.System_State, w1.System_Rev,
        row_number() over(partition by w1.System_Id, w1.TeamProjectSK order by w1.System_Rev desc) rn
    from dbo.DimWorkItem w1  
    where w1.System_Id = 1691  
) d
where rn = 1;

---

看

我想要一些不同的东西，但它很有帮助。它帮助我更好地理解了如何使用分区。

select System_Id, TeamProjectSK, System_State, System_Rev
from
(
    select w1.System_Id, w1.TeamProjectSK, w1.System_State, w1.System_Rev,
    row_number() over(partition by w1.System_Id, w1.TeamProjectSK, w1.System_State order by w1.System_Rev desc) rn
    from dbo.DimWorkItem w1  
    where w1.System_Id = 1691
) d
where rn = 1
and d.System_Rev = (select max(w2.System_Rev) from dbo.DimWorkItem w2 where w2.System_Id = d.System_Id)
order by System_Id, TeamProjectSK,System_Rev desc;