Would it be feasible to create a sequential record number for each week?
e.g.
week weekID
1 1
5 2
9 3
17 4
19 5
You could probably add this ID in your load script to your table (for example using recno() function). If your actual data is more granular (e.g. based on days), you could create a linkage table with the unique weeks and then create weekIDs.
If you got them, your sum could look like this:
=sum({<weekID={">$(=max(weekID)-4)<=$(=max(weekID))"}, week= >} VALUE)
This is a set expression which selects (only for this expression, not globally in your application) the weekIDs which are between max(weekID) and max(weekID)-4. max(weekID) should give you the ID of user selected week.
Regards,
Stefan
