DAX Deep Dive 02 : Calculated Column vs. Measure – The Essential Difference Every Power BI Pro Must Know
The first step to mastering DAX is understanding the "identity of a value." You must clearly define whether what you are creating is "fixed historical data" or a "real-time response" that changes based on a user's question. 1. Calculated Column: A Fixed State Determined at Data Loading A Calculated Column is computed row by row during the data refresh process and is physically stored as a value within the data model. Once calculated, it does not change based on slicers or filters in the report. Calculation Timing: Performed only once during the data refresh. Operating Principle (Row Context): It scans each row one by one and completes the calculation using only the values present in that specific row. System Characteristics: Slicers or filters on a report cannot change the "result value" of a Calculated Column. Slicers merely determine "which rows to show" (Visibility). Primary Uses: Values to be used as slicer items (e.g., Age Gr...