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Category: DAX

DAX Formatter for Power BI Desktop

Published 2020-11-24 by Kevin Feasel

Phil Seamark has a new tool for us:

Last week I was honoured to take part in the latest edition of the Power BI Dev Camp which is run by my colleague Ted Patterson. It was a fun session which I enjoyed.

As part of the Dev camp, I walked through some of my recent Visual Studio Code based blog posts on how to perform various tasks against models hosted in Power BI desktop.

While preparing for the session, Ted and I agreed that it might be helpful to create a small external tool that could automatically format all DAX expressions in a Power BI model. The idea is to leverage the excellent DAX Formatter API provided by the good folks at SQLBI. This API is the same endpoint used when you format your DAX using DAX Studio.

Read on for more details.

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Using the Vertipaq Analyzer with DAX Studio

Published 2020-11-12 by Kevin Feasel

Gilbert Quevauvilliers walks us through the Vertipack Analyzer in DAX Studio:

If you are looking to better understand your Power BI Model, how big are your tables, which column is taking up the most space then you can use Vertipaq analyzer which is built directly into the amazing DAX studio.

If you are looking for a video on how to do this, there are some awesome videos found here.

SQLBI.COM – Introducing VertiPaq Analyzer in DAX Studio

Guy In a Cube – How do you even use VertiPaq Analyzer with Power BI???

The reason for my blog post, is that I find sometimes I want to watch a video to better understand the content, and other times I want to follow a step by step process on how complete the analysis.

Click through for a walkthrough of the process.

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Getting Power BI to Write Your DAX

Published 2020-10-23 by Kevin Feasel

Gilbert Quevauvilliers shows off an interesting way of using a Power BI feature:

Recently I had to get some data from a Power BI Dataset. At first, I started writing the DAX using the fantastic DAX Studio.

Then a thought occurred to me, what if I could get the DAX already written and change it to my requirement. This would save me a lot of time and effort. I love the quote from Patrick in Guy in a Cube “I am not lazy, I am efficient”

Click through for the scenario. Looks like it will get you at least part of the way there.

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Dynamic Format Strings when using Calculation Groups

Published 2020-10-21 by Kevin Feasel

Alberto Ferrari shows off how you can dynamically generate format strings when using calculation groups in Power BI:

Each product in Contoso weighs a certain weight. The weight is stored in two columns: the unit of measure and the actual weight, expressed in that unit of measure. Specifically, Contoso uses three units of measure: ounces, pounds, and grams.

Because the units of measure are different, you cannot aggregate the weight over different products. If you author a simple measure that computes the ordered weight of products by using a simple SUMX, the result is wrong:

Click through to see how you can work through this problem.

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Set Functions in DAX

Published 2020-10-13 by Kevin Feasel

Marco Russo and Alberto Ferrari walk us through three important set functions in DAX:

In this article we refer to “set functions” as functions that operate on sets. The three set functions available in DAX are: UNION, INTERSECT, and EXCEPT. Their behavior is very intuitive:

– UNION performs the union of two or more tables.
– INTERSECT performs the set intersection between two tables.
– EXCEPT removes the rows of the second argument from the first one.

These functions take two or more tables as parameters and return a table. They prove useful not only to write DAX queries; a developer can also use these functions to prepare complex filters when implementing measures.

Read on to see how these work in DAX.

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DAX Financial Functions

Published 2020-09-21 by Kevin Feasel

Bill Pearson begins a series on financial functions inside DAX:

As a part of this introduction, you’ll have an opportunity to examine how each function can be employed to support business requirements of the sort that your hypothetical colleagues encounter routinely, and, for the most part, accomplish with Microsoft Excel, in meeting regular business requirements. You’ll learn the purpose of each function, and then undertake a practice example with each that demonstrates how it interacts with a small loan data set, via a calculation that you construct. Moreover, you will:

– Examine the syntax involved in exploiting the function.
– Undertake an illustrative example of the use of the function in a practice exercise.
– Review a brief discussion of the results you obtain in the steps of the practice example.

This is a thorough opening article.

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MAX Versus LASTDATE in DAX

Published 2020-09-15 by Kevin Feasel

Alberto Ferrari explains why you might want to use MAX() instead of LASTDATE() to find the latest date in a table with DAX:

Many DAX newbies use LASTDATE to search for the last date in a time period. Or they use NEXTDAY to retrieve the day after a given date. Although these functions do what they promise, they are not intended to be used in simple expressions. Instead, they are table functions designed to be used in time intelligence calculations. Using them the wrong way leads to inefficient code. Moreover, using these functions in ways they were not designed for is a telltale sign that the developer still does not grasp certain details of DAX.

In this article, we elaborate on the topic in order to understand what these time intelligence functions do; we also want to understand the reason why it is so easy to confuse them with simple math over dates. We want to elaborate on this topic through examples. Therefore, instead of starting with boring theory, we start by looking at a calculation that – although it works perfectly fine – is inherently wrong.

Read on for that explanation.

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