Question

I’m having trouble getting a query to work. What I’m trying to do is sum a counter by user id but with conditions.

Currently my query gives the following output.

User ID  EndDate    Date       Index
 123      5/1/12   1/1/12       -1
 123      5/1/12   1/25/12       1
 123      5/1/12   2/13/12      -1
 456      4/1/12   1/18/12      -1
 456      4/1/12   2/15/12      -1
 456      4/1/12   2/18/12       1

What I want to do with this list is sum the Index by User Id but with a catch. The Index must be summed in date order, also the min value of the index is -1 and max is 1, so the values can be -1, 0, 1 only. So with user 123, the process would be -1 then you add 1 then you add -1 for a final sum of -1. But for user 456 you start with -1 then you have -1 again but the sum must remain -1 then you have 1, so the final sum is 0. Below is what I’m been trying to do but I can’t figure it out. I would really appreciate some help.

DECLARE @Period char(6)
DECLARE @StatusCount int
    SET @Period = '201201'
    SET @StatusCount = 0

SELECT     Q1.UserID, Q1.End_Date,
            Sum(Case 
                When Index = -1 Then Case When @IndexCount >=0 Then @IndexCount - 1 Else @IndexCount + 0 End
                When Index = 1 Then Case When @IndexCount <=0 Then @IndexCount + 1 Else @IndexCount + 0 End
            END) as FinalIndex

FROM 
(
    (SELECT    UserID,  End_Date, Enter_Dt, 1 as Index
    FROM        UserTable 
    WHERE       (Code in ('A', 'B') and PRD = @Period)
    GROUP BY    UserID,  End_Date, Enter_Dt)

         UNION

    (SELECT     UserID,  End_Date, Enter_Dt, -1 as Index
    FROM         UserTable 
    WHERE     (Code in ('C', 'D') and PRD = @Period)
    GROUP BY    UserID,  End_Date, Enter_Dt)
) as Q1

GROUP BY Q1.UserID, Q1.End_Date
ORDER BY Q1.UserID ASC, Q1.End_Date ASC

I think my main problem is I can’t figure out how to accumulate the Index properly. I can’t get IndexCount to remember the the previous value and then start again from 0 with the next User ID

The result I get with this query is

User ID    EndDate       Index
 123       5/01/12       -1
 456       4/01/12       -1

Which is just summing the Index

Answer 1

I’ll illustrate a running total by userID solution here, leaving out the other details of your query for clarity. Basically, add a IndexRT column populate it with a running total that resets for each new userID.

EDIT: constrain running total to -1,0,1

create table #temp(userID int, [Index] int, IndexRT int) 
insert into #temp (userID,[Index]) values (123,-1) , (123,1) , (123,-1) , (456,-1) , (456,-1) , (456,1)  
declare @rt int; set @rt=0;

with a as (
    select select TOP 100 percent *
    ,r=ROW_NUMBER()over(partition by userID order by userID) 
    from #temp order by userID,ROW_NUMBER()over(partition by userID order by userID) 
) 
update a set @rt = [IndexRT] = case when case when r=1 then [Index] else @rt + [Index] end between -1 and 1
then case when r=1 then [Index] else @rt + [Index] end
else @rt
end

select * from #temp;
go 
drop table #temp;

Result:

userID      Index       IndexRT
----------- ----------- -----------
123         -1          -1
123         1           0
123         -1          -1
456         -1          -1
456         -1          -1
456         1           0