Have attached workbook with workaround, let me know if it helps, in that case you can mark it as answered/helpful. otherwise you can give some more insights.
tableau_doubt_v10.2.twbx 124.3 KB
I know you may know this workaround already, but I think the best practice is to join your data to a table with all year listed as shown below
Hope this helps
tableau_doubt_v10.2.twbx 142.4 KB
Thanks for your help.
I was checking your file to see if everything was ok, as well as to try and understand your methodology, but I noticed the acumulated history was not quite right. As you can see on the table below (only D courses), the first one was created in 81 (1), then another in 84 (2), two more in 87 (4), two in 88 (6), one in 89 (7), and so on.
But you see that the field generated to count active courses did not count the 1989 course which was closed in 2002 (since the StatusToday is fixed, showing only how is the status of the course today). What I needed was this 1989 course to count until 2002, and then not count starting in 2003. With that, the results ended up being similar to just filtering out courses that are no longer OPEN.
But thanks anyway. I will try to explore some workaround using your approach.
Thanks for the tip.
This would be actualy easier and more dynamic from the approach I would do with a second table (which would require counting active courses per year and exporting results and importing the table back to Tableau) but would also generate a problem for me. Since I'm working with a 7000 line table (with over 100 columns of distinct data about the courses and some other tables to associate to them), I would end up multiplying my database by the number of years in the analysis (since 1931, in the full set).
Anyway, if I can't find the result I'm hoping for, at least I can create a secondary dataset, with only selected columns, to get the job done.