Question

SCENARIO:
Imagine a TABLE like this:

Auto_INC, UserID_FK, CaseID_FK,    Date
   idX      userX      caseX

and when it is filled, it looks like this:

   id1,     user4,     case20,   2010/01/12  
   id2,     user1,     case13,   2010/03/20  
   id3,     user2,     case10,   2010/03/22  
   id4,     user1,     case21,   2011/01/10  
   id5,     user2,      case9,   2011/01/11  
   id6,     user3,     case20,   2011/02/01  
   id7,     user1,      case9,   2011/03/25

QUESTION:
How do i get ONE CASE Record with the LAST User Assigned ??

So if one user has been assigned, it will automatically override all previous users on that case.

Something like this:

   id7,     user1,      case9,   2011/03/25  
   id2,     user1,     case13,   2010/03/20  
   id4,     user1,     case21,   2011/01/10
   id6,     user3,     case20,   2011/02/01    
   id3,     user2,     case10,   2010/03/22  

In this case User1 has been assigned to 3 cases, User2 to 2 cases but one was overridden by User1, User3 had 1 case and it did override User4 …so User4 does not get any case ..therefore it will NOT appear on the list.

NOTE BENE
Ideally we should be getting as result ..as many records as there are CASES on the original table !!!

Answer 1

declare @T table
(
  Auto_INC int identity primary key, 
  UserID_FK int, 
  CaseID_FK int,
  [Date] date
);

insert into @T values
(4, 20, '2010/01/12'),
(1, 13, '2010/03/20'),
(2, 10, '2010/03/22'),
(1, 21, '2010/01/10'),
(2, 9,  '2010/01/11'),
(3, 20, '2010/02/01'),
(1, 9,  '2010/03/25');

with C as
(
  select *,
         row_number() over(partition by CaseID_FK 
                           order by [Date] desc) as rn
  from @T
)
select Auto_INC, UserID_FK, CaseID_FK, [Date]
from C
where rn = 1;

Result:

Auto_INC    UserID_FK   CaseID_FK   Date
----------- ----------- ----------- ----------
7           1           9           2010-03-25
3           2           10          2010-03-22
2           1           13          2010-03-20
6           3           20          2010-02-01
4           1           21          2010-01-10