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

Summary

While most of the DAX challenges you will face, and most of this book's chapters, are fundamentally about context, or what is being calculated, this chapter focused on which calculations are done to populate a visual from a Power BI model.

Power BI applies AutoExist to guess the combinations of label values to evaluate. The simple rule is:

  • When columns from the same table are used in a visual, only combinations of column values that are found in rows of the table are evaluated.
  • When columns from different tables are used, all combinations of values are evaluated.

Understanding how AutoExist works will help you to find out why you sometimes do not see results in a visual when, logically, you would expect them. It also helps to avoid performance problems in reports that are the result of using too many columns from too many tables in one visual. An important lesson is this: be careful with table visuals!

The next chapter returns mainly...