chapter one

1 Understanding the language behind Power BI

 

This chapter covers

  • What DAX is and how it fits into the Power BI and Fabric ecosystem
  • What interactive DAX is and how it differs from SQL and other languages
  • Why user interactions generate hidden filters in your measures
  • How Power BI’s semantic model shapes every DAX result
  • The tools and conceptual skills you will use throughout this book

DAX has always had a reputation for being powerful, elegant, and occasionally baffling. Even experienced developers have moments where a measure works in one visual but changes unexpectedly in another. A total looks wrong. A slicer overrides business logic. A seemingly harmless interaction reshapes an entire calculation, and you are left wondering why.

This experience is not a failure of DAX. It is a misunderstanding of its environment.

DAX is not a typical formula language. It does not operate like SQL, executing a fixed query, or like Excel, calculating directly from cell references. Instead, DAX evaluates your logic inside a semantic model that is constantly reshaped by user interaction.

1.1 A modern definition of DAX

1.2 Why DAX matters for modern analytics

1.3 What problems does DAX solve?

1.4 Who this book is for, and what you will learn

1.5 How this book teaches DAX

1.6 The mental model: how DAX evaluates a measure

1.7 Interactive DAX

1.8 User roles that influence DAX

1.9 How interaction works: A scenario in which a simple measure meets a live report

1.10 Asking the right questions

1.11 The art of interactive DAX

1.12 Why interactivity matters more in the age of LLMs, MCP servers, and agentic systems

1.13 Summary