Hi Daniil,
came across your report. Besides you just schattered my confidence that I was on a good way to understand a bit of DAX, the quiz is great. I understand that you intentionally built the example, but it can happen in the real world as well -> https://sqlkover.com/sumx-returns-incorrect-results-with-duplicates/
Unfortunately I do not understand all your explanations (yet) and Alberto's posts made my head even more spinning. I am very confused, as a beginner we use COUNTROWS and SUMX a lot and we are proud of ourselves, that we finally get some nice visuals out of it. Now it seems we cannot trust even the simplest calculation without doublechecking the results in Excel (which brings us back to 1987). Then what's the point of having DAX, if SUMX returns 7 (question 3) in a data set of 1,3,1 (which ... for me ... totals still 5, unless the earth spinns the other way around); I tripplechecked on my old fashion calculator and it says 1+3+1=5, I intend to believe that.
Ok, stop whining ... here are my questions:
For comparison reasons and following the tip from Koen, I built your example with an index column, which solved most, but not all problems (-> VAR).
Question 2 color filter
I learned, that the "DAX onion" is eaten from the inside out, meaning complex DAX is executed from inside to outside.
From that understanding the result should be blank.
First the "inside" CALCULATE returns a distinct list of values (colors) which is then filtered down to only "Black".
Then the "outside" CALCULATE shall return "White". But as there is no "White" after step 1, it shall return Blank.
What's wrong with that (my) thinking?
Question 5 VAR
I read a lot about strange behavior of VAR and wrong results. VAR is a wonderful tool to structure DAX code, but how can I make sure, that the result does not come out rubbish?
Many thanks in advance
