dAx

DAX stands for Data Analysis Expressions, a formula language used to define calculations in Microsoft Power BI, Excel Power Pivot, and SQL Server Analysis Services Tabular models. Introduced to provide a consistent calculation framework across self-service BI and enterprise BI, DAX builds on Excel-style functions while incorporating the concept of evaluation context to support dynamic analysis of data.

DAX enables the creation of calculated columns, measures, and calculated tables. Calculated columns compute values at data load time, while measures perform aggregations during query time. DAX expressions use a combination of functions, operators, and constants. The CALCULATE function is central, changing the filter context to influence how expressions are evaluated. Other common functions include SUM, AVERAGE, MAX, MIN, FILTER, and time-intelligence functions such as TOTALYTD, SAMEPERIODLASTYEAR, and DATESINPERIOD.

The language is designed for columnar data models and emphasizes context transition and relationships between tables. DAX expressions are typically evaluated in models with relationships, columns referenced from surrounding tables, and a syntax that resembles a mix of Excel formulas and SQL-like syntax.

DAX also refers to the Deutscher Aktienindex, commonly called the DAX, which is a German stock market index. It tracks the performance of major German blue-chip companies listed on the Frankfurt Stock Exchange. The index began as DAX 30 and was expanded to 40 constituents in 2021, after which it is often referred to as DAX 40.