I am trying to do a rolling 13 week sum on a specific field in the load script (see attached image), as the expression/set analysis I have, while working, is significantly slowing down the report. I spent some time looking at the other related questions on the forum, but am still having some difficulty understanding how to write it out. Most related questions revolve around taking the whole sum, not broken down by a specific time-frame (in my case, 13wks).
Would anyone be able to help me understand how to write in the load script a rolling 13 wk sum on the Quantity field, aggr by Product and YYYYWK? I know I would have to do a Group by, but since I had it by PRODUCT and YYYYWK in the set analysis, what about the other fields (YYYYQ, KEY).