Master the Data Analysis Expressions language.
14 tutorials in this category
Most slow Power BI reports are slow because of DAX, not the model. Learn the 10 optimization patterns that fix the majority of DAX performance problems, with copy-paste measures and Server Timings context.
DAX UDFs went GA in June 2026. Learn how the FUNCTION keyword lets you package reusable parameterized logic — tax calculations, currency conversion, margin formulas — and call it from any measure or column.
Visual Calculations went GA in May 2026. Learn how RUNNINGSUM, MOVINGAVERAGE, PREVIOUS, and other visual-level functions replace dozens of measures — with real Contoso examples and copy-paste code.
CALCULATE is the most powerful function in DAX, and the one most often misunderstood. This guide covers how filter context works, how CALCULATE modifies it, the four most common patterns every analyst needs, and the mistakes that produce silently wrong numbers.
DAX variables make complex measures readable, prevent repeated calculations, and eliminate an entire class of context-transition bugs. This guide covers the syntax, scope rules, four practical patterns, and the performance gains you get from using variables correctly.
SWITCH replaces messy nested IF statements in DAX with clean, readable conditional logic. Learn the syntax, four practical patterns, and the mistakes that cause SWITCH to return blank results.
RANKX is the DAX function for ranking rows by any measure or expression. This guide covers the syntax, the four ranking patterns every analyst needs, ties handling, and the common mistakes that produce wrong results.
DAX errors are notoriously unhelpful. This guide covers the 15 most common DAX errors — from blank results to wrong totals to circular dependencies — with exact before-and-after fixes you can copy-paste.
Every Power BI beginner makes the same mistakes. This guide covers the 10 most common errors — from data types to DAX context to dashboard design — with exact fixes you can apply today.
Variables in DAX do more than make code readable — they cache intermediate results, prevent repeated calculation, and make complex logic testable. This guide covers the syntax, the performance benefit, and five patterns where variables transform unreadable measures into maintainable code.
SUM is simple and fast. SUMX is flexible and powerful. Choosing the wrong one leads to incorrect totals or bloated models. This guide covers the difference, when each is appropriate, and the three patterns where SUMX is the only correct choice.
Filter context and row context are the two evaluation contexts that govern every DAX formula. Most calculation errors trace back to confusing them. This guide breaks down both, shows how they interact, and gives you the mental model to predict formula behavior before you write it.
CALCULATE is the only function that can modify filter context. Master its syntax, evaluation order, and three real-world patterns that unlock every advanced DAX formula.
Learn what DAX is, how measures differ from calculated columns, and write your first five formulas with confidence. A practical starting point for every Power BI analyst.