Video by: Reid Havens
The single biggest concept separating DAX beginners from confident report builders is context. This interactive guide breaks down how Power BI evaluates every formula you write: what filter context is, how CALCULATE manipulates it, the difference between row context and filter context, how context transition bridges the two, and why iterator functions like SUMX create their own row context. If CALCULATE has ever confused you, start here.
Topics covered:
The mental model shift: why DAX doesn't think like Excel
Query context: how rows and columns shape evaluation
Filter context: slicers, relationships, and implicit filters
CALCULATE: overriding, replacing, and adding filter arguments
Row context: calculated columns, iterators, and the current row
Context transition: what happens when CALCULATE meets row context
Iterator functions: SUMX, AVERAGEX, and row-by-row evaluation
