使用来自多个SQL的数据选择MAX date

Question

我知道这是一个很受欢迎的问题,我已经了解了现有的情况,但我相信我的情况有点独特(如果不是,请指出我正确的方向).

我正在尝试查找当前跨两个表和多个列与用户关联的最新行.

table: statusUpdate
+-------+-----------+-----------+-------------------+
|   id |    name    |   status  |       date_change |
+-------+-----------+-----------+-------------------+
|   1   |   Matt    |       0   |   01-01-2001      |
|   2   |   Jeff    |       1   |   01-01-2001      |
|   3   |   Jeff    |       2   |   01-01-2002      |
|   4   |   Bill    |       2   |   01-01-2001      |
|   5   |   Bill    |       3   |   01-01-2004      |
+-------+-----------+-----------+-------------------+

table: relationship
+-------+-----------+--------------+
|   id  |   userID  |stautsUpdateID|       
+-------+-----------+--------------+
|   1   |   22      |       1      |   
|   2   |   33      |       2      |   
|   3   |   33      |       3      |   
|   4   |   44      |       4      | 
|   5   |   44      |       5      | 
+-------+-----------+--------------+

有一个第三个表将userID链接到它自己的表,但这些样本表应该足以让我的问题结束.

我希望按日期获得最新的状态更改.目前的问题是它返回状态更改的所有实例.

Current results:
+-------+---------+-----------+-------------------+
|userID |statusID |   status  |       date_change |
+-------+---------+-----------+-------------------+
|   33  |   2     |       1   |   01-01-2001      |
|   33  |   3     |       2   |   01-01-2002      |
|   44  |   4     |       2   |   01-01-2001      |
|   44  |   5     |       3   |   01-01-2004      |
+-------+---------+-----------+-------------------+

Expected results:
+-------+-----------+-----------+-------------------+
|userID |statusID   |   status  |       date_change |
+-------+-----------+-----------+-------------------+
|   33  |   3       |       2   |   01-01-2002      |
|   44  |   5       |       3   |   01-01-2004      |
+-------+-----------+-----------+-------------------+

我希望这一切都有意义,请另外询问更多信息.

重申一下,我只想按日期返回用户状态更改的最新实例.

Sample code of one of my attempts:

select 
st.ID, st.status, st.date_change, r.userID 
from statusUpdate st
inner join Relationship r on st.ID = r.statusUpdateID

inner join (select ID, max(date_change) as recent from statusUpdate
group by ID) as y on r.stausUpdateID = y.ID and st.date_change = 
y.recent

希望有人能指出我正确的方向.

Answer 1

用于row_number()获取用户的最后一行

select *
from
(
select st.ID, st.status, st.date_change, r.userID,
       rn = row_number() over (partition by r.userID order by st.date_change desc) 
from   statusUpdate st
       inner join Relationship r on st.ID = r.statusUpdateID
) as d
where rn  = 1