Book Image

Extreme DAX

By : Michiel Rozema, Henk Vlootman
Book Image

Extreme DAX

By: Michiel Rozema, Henk Vlootman

Overview of this book

This book helps business analysts generate powerful and sophisticated analyses from their data using DAX and get the most out of Microsoft Business Intelligence tools. Extreme DAX will first teach you the principles of business intelligence, good model design, and how DAX fits into it all. Then, you’ll launch into detailed examples of DAX in real-world business scenarios such as inventory calculations, forecasting, intercompany business, and data security. At each step, senior DAX experts will walk you through the subtleties involved in working with Power BI models and common mistakes to look out for as you build advanced data aggregations. You’ll deepen your understanding of DAX functions, filters, and measures, and how and when they can be used to derive effective insights. You’ll also be provided with PBIX files for each chapter, so that you can follow along and explore in your own time.
Table of Contents (17 chapters)
Free Chapter
1
Part I: Introduction
6
Part II: Business cases
15
Other Books You May Enjoy
16
Index

Table functions in DAX

There is a lot you can do with basic aggregation functions like SUM and AVERAGE, in combination with DAX filtering using CALCULATE. But the DAX language goes beyond that. This section is about table functions, which open up an ocean of more advanced calculations in DAX. In Part 2 of this book, you will find that many of the business scenarios discussed involve DAX table functions.

Table aggregations

To start, let's look closely at a simple aggregation in DAX:

Sales1 = SUM(fSales[SalesAmount])

The SUM function in this formula traverses the fSales table and retrieves the value in the SalesAmount column from each row. All these values are summed up to provide the end result.

Because of the special way a Power BI model encodes and stores data (see Chapter 1.2, Model Design), this may not be what happens technically. Logically, however, this is what SUM does, and that is what we are interested in here.

Now, suppose the...