I can use either SQL Server or Vertica as the DB and Tableau as the reporting tool. A solution in any of these mediums would be helpful.
DATA RESOURCES: I have a table (userActivity) with 100 records and a structure of User, StartDate, EndDate
NEED: I am interested in preparing reports by day and month that show "total active days", meaning if User1 has a range of '20180101' to '20180331', they will contribute one day for each day in Jan, Feb, and Mar OR 31, 28 and 31 days if aggregated by month.
GOAL: I will ultimately be aggregating the total active days of all users as the output to achieve a single total for each day/month.
This report will span to perpetuity, so I would prefer solutions that don't hard code CASE/IF-THEN statements by day/month.