Sometimes, as a beginner to Power BI, it is really hard to know where to start applying your efforts. Not least of the Herculean efforts is learning DAX. And, because it is so hard to know where to start, it is understandable if one defers this task. That’s not a good idea. By the time you need DAX, it can be hard to master it fast enough. With this in mind, I have put together a list of what I consider the top 10 DAX functions. I didn’t do this on my own–I crowd sourced it with my #SML* crew, whose opinions I give more weight to than my own!
SUM and SUMX
When you understand why you see SUM (or another aggregating function) in front of a column name so frequently helps you understand that DAX works at the column level.
I chose this one because right after understanding the basics of filter context, it is important to understand how to modify the filter context intentionally
I chose these three because probably the hardest thing to do when you are just starting out is to construct a simple, elegant star schema. I think newbies want to make relationships bi-directional to solve problems that could be solved by understanding the following three DAX functions. Each of these can traverse a very streamlined model without ‘janking’ (technical term) it up.
COUNTROWS (Courtesy of Sue Bayes)
Countrows because you are always asking questions about number of occurrences / events happening filtered by specific “things”
DISTINCTCOUNT (Courtesy of Cristian Angyal)
This is the natural companion to COUNTROWS. We sometimes want to count how many unique instances of a value is present.
VALUES (Courtesy of Cristian Angyal)
If you want to see (not just count) the number of unique values that are present, VALUES can do that for you.
FILTER (Courtesy of Cristian Angyal)
This useful function returns a subset of values from anther table or expression.
ALL (Courtesy of Cristian Angyal)
Because it is easy to apply a filter without knowing it (remember, every visual is in effect, a filter, knowing the function to clear any existing filters is invaluable.
What are the top 10 DAX functions that you believe every beginner should master?
* I run a Team where folks who are always wanting to learn more about Power BI can join, for free. We chatter on various channels about all things Power BI. We pick technical books related to Power BI and we meet every other Saturday to review our learning–Saturday Morning Learning (#SML). You are welcome to join us. The only requirement is a desire to always be learning. Just use my Contact form to connect with me, or find me on LinkedIn.