When learning DAX, time intelligence formulas are an excellent place to start, and of the many formula patterns out there, “Year to Date” variations might be the best to learn first. The problem is, while writing them is fairly easy, understanding how they work can still be very tricky.
In this video, we take a simple YTD measure with a very simple model and walk through what's happening behind the scenes step by step so you can get a more solid understanding of how it works, which will help you understand how DAX works in general. We go through some tricky DAX concepts, but because they are laid out in front of you, they can become much easier to understand and then learn.
Link to the walk through file can be found here