DAX Deep Dive 06 : Why a Single VAR Changes the Result in DAX: The Difference Between Inside vs. Outside CALCULATE
When working with Power BI, you will eventually encounter a moment where you ask: "It's clearly the same logic... so why are the results different?" Specifically, the experience of getting completely different results depending on whether you used a VAR or not is an almost essential rite of passage for practitioners. This issue is not a simple difference in syntax; it is deeply connected to the Evaluation Timing of the DAX engine. This article clarifies this difference and explains structurally why results vary inside and outside of CALCULATE. 1. The Essence of the Problem: "Same Code, Different Results" Let’s compare the following two codes. The goal is to calculate the 'Average of the last 4 months from the current point.' 1) Case 1: Direct Evaluation Inside CALCULATE (Normal Operation) This method works exactly as we intended, escaping the influence of the sl...