I'm an absolute newbie at this and about to make a complete fool of myself I expect but...
I have a table showing total sales this year for a week, total sales last year for the same week, and I also want period to date for this year and last year.
Week, period and year are all variables named ThisWeek, ThisPeriod and ThisYear (ther is also one for LastYear)
Currently the expression looks like this:
Sum (IF(DWH_OP_WEEK <=ThisWeek
It works fine for period to date at the end of the period, but if I want to look back at week 2 period 1 for example, it still shows me total Period To Date for the whole period (when i only want to see the Period to Date up to week 2).