Category: DAX

Marco Russo and Alberto Ferrari do some ranking:

Ranking is one of the most frequent calculations in Power BI reports. Needing to determine the top products, countries, customers and such is extremely common. RANKX offers a powerful and very fast way to produce ranking. Nonetheless, its use takes some understanding.

In this article we introduce the RANKX function and provide a few interesting examples of how it can be used. RANKX is not a complex function to learn. Nonetheless, most newbies find it intimidating because they do not fully grasp its internals. Once they learn exactly how RANKX works, its use becomes really simple.

Click through to learn how it works.

Marco Russo and Alberto Ferrari explain how the ALLSELECTED function works:

There are two ways to describe what ALLSELECTED performs and what its use cases are: a simple way and a complex way. In this article, we focus on a simple description of the function and its main use cases. We also provide details about when and how you can use ALLSELECTED without having to worry about the intricate details. If and when you want to go to the next level, invest the proper amount of time required to study this article: The definitive guide to ALLSELECTED. Be careful, the details are really complex and if you stick to the best practices, you can safely ignore said details. A real DAX guru should know all the details, but in this article we focus more on an introduction to ALLSELECTED.

Because of its inherent complexity, we describe ALLSELECTED by first focusing on a business case where ALLSELECTED is a good fit. We then provide an imperfect – yet useful – description of what ALLSELECTED is performing. And finally we provide the few best practices to follow when using ALLSELECTED. We will not provide the complete description of ALLSELECTED in terms of shadow filter context, not even as an introduction.

Even the simple solution is fairly complex.

Jeffrey Wang wraps up a series on the EvaluateAndLog function:

This is the fourth and the last article on the EvaluateAndLog function. While DAX developers were excited about the prospect of printing the values of a portion of a DAX expression, many of the early adopters of the function were puzzled by a mysterious message they ran into from time to time: “EvaluateAndLog function is not executed due to optimization.” Another question on people’s mind is “While it’s great to be able to see the values of a sub-expression used in my calculation, is there a way for me to see the values of other expressions which are not needed to calculate the final result?” I will provide answers to both questions in this post.

Click through to understand why you might get this message and what it means.

Alberto Ferrari and Marco Russo add some context:

RELATED is one of the most commonly used DAX functions. You use RELATED when you are scanning a table, and within that row context you want to access rows in related tables. RELATEDTABLE is the companion of RELATED, and it is used to traverse relationships in the opposite direction. When learning DAX, it is easy to get confused and use RELATED when it is not necessary, or to forget about RELATEDTABLE. In this article, we describe the most common uses of the two functions, along with common misperceptions.

Click through to learn more about these two functions.

Jeffrey Wang continues a series on EVALUATEANDLOG():

Last week, we learned how to interpret the output of the EvaluateAndLog function of scalar expressions. Albeit interesting, the new function would be much less useful if it could only return scalar values. After all, Power BI users can always define a scalar expression as a measure and then study its values in various contexts. The real power of EvaluateAndLog is that it can also wrap around any table expressions, the output of which was much harder to visualize until now.

This function exposes a lot of information, as you can see in the post.

Marco Russo has an announcement:

DAX Studio 3 was released today.

This new, major version offers a new user interface and user experience, providing a modern look and feel without losing any of the features available in previous versions. On the contrary, in DAX Studio 3, many features that were harder to reach in the past are now more visible and easier to use.

The cost of implementing a complete overhaul for a product’s user interface is typically high, but at the same time, this overhaul does not provide new features compared to previous versions. So why bother about the user interface while the product is free and open-source?

Read on to see what those changes look like.

Chris Webb is excited:

I think this is the most exciting thing to happen in DAX since the introduction of variables. Why? Well we all know that writing DAX can be hard, and part of why it’s hard is that it’s hard to debug.

Read on to see how EvaluateAndLog() makes life easier, as well as a couple links to Jeffrey Wang’s blog for further detail.