Data Analysis Expressions (DAX)

DAX is a formula language. You can use DAX to define custom calculations for Calculated Columns and for Measures (also known as calculated fields). DAX includes some of the functions used in Excel formulas.

Calculated Columns

• Formula is evaluated for each row
• Results are stored back into PowerPivot as any other column
• Columns can be used for both slicing data and summarizing values

Calculated Measures

• Evaluated dynamically per value in PivotTable
• Part of the model, available to other PivotTables.

I won't go much more in theory, the best way to learn DAX calculations is by working on it. So, lets start creating measures and calculated columns.

For more details on DAX oveview you can check Microsoft's Power BI documentation:

DAX Basics

Let's begin!