I chose to do this session (instead of another one that was initially planned) because when I looked at PASS agenda I found that a session about DAX foundation was missing, and this wasn’t good. In fact, you might be able to write a DAX expression (and, most important, to control it!) only after you really understood how evaluation context works in DAX. The evaluation context is formed by two parts: row context and filter context. Writing the book, I learnt them the hard way, by making all the possible mistakes that you might be able to do, and probably more. For this reason, I tried to describe these concepts in the way I would have loved to learn the first time. I dedicated a whole chapter to it and it is challenging trying to transfer the same concepts in one hour. But I know that it does worth the effort, because the need for this knowledge will increase approaching to the next version of Analysis Services.
Well, see you at PASS or at the PowerPivot Workshop if you are based in Europe!
Originally appeared on: http://sqlblog.com/blogs/marco_russo/archive/2010/10/15/inside-dax-session-at-pass.aspx