Use Calculated Table to Figure out Monthly Subscriber Churn

Power BI Desktop 2015 SU09 introduced a really cool new feature called calculated tables. Those of you who are already familiar with calculated columns will share my excitement since we now have a flexible, intuitive, and visual way of solving common business problems which were very hard, if not impossible, to tackle previously. Today I am going to show you how to leverage calculated tables to display monthly total number of subscribers starting from a table listing each user account's start and end dates. The sample data is taken from Kathi Kellenberger's blog post T-SQL Window Functions Speed Phreakery. If you are a SQL junkie, you should read Kathi's blog to learn a few clever ways of writing ever faster T-SQL queries to calculate monthly total subscriber numbers from the original data. A sample of the source data is shown in Figure 1.