1 Reply Latest reply on Aug 23, 2016 3:23 PM by Stoyko Kostov

    What function to use??

    Nick Fordham

      Hi All


      I'm looking for guidance on the appropriate tableau function to use for my challenge:


      I have a database that records the date that a customer was placed on a waiting list and the date that a customer was removed from the same waiting list - these are two separate fields.


      I want to perform a running tally of the number of customers on the waiting list at the end of each month and show this as a trend graph month by month by month (as a single visualisation).....


      Customers are regularly on this waiting list for several months, so a 'CASE' or 'IF' statement wont work as it only counts each record once - but a person on the waiting list for several months will need to contribute to the count/ totals of several month's values.


      So, how do I perform this?



        • 1. Re: What function to use??
          Stoyko Kostov

          Hi Nick,


          There was a similar question about a month ago - tracking employees with start and exit dates - and I recommended using self-join.


          Take a look here: Using two date fields to create trend across time


          There are additional links in the article which may be able to help.


          Once you set up your data correctly, the function you should use is just COUNT. You would count the users whose start waitlist times are before the end of the current month, and end waitlist times are after the beginning of the current month.


          I hope you can make sense of this. If not, it would help me if you could attach a sample packaged workbook, and I'll use it to try to find a solution. Let me also know if your data source would allow you to do a self-join.