Data Analysis Expressions (DAX) in Power BI

Introduction

By using Data Analysis Expressions (DAX), you can add three types of calculations to your data model:

• Calculated tables

  • Date tables

  • Role-playing dimensions

  • What-if analysis

• Calculated columns

• Measures

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Calculated tables

Power BI, a powerful business intelligence tool developed by Microsoft, allows users to create Calculated Tables. A calculated table is a virtual table that is defined using Data Analysis Expressions (DAX) and is derived from existing physical tables. Unlike the imported physical tables from external data sources, calculated tables are created based on specific requirements using DAX expressions. These calculated tables behave like regular tables and can have their own data types, formatting options, and relationships with other tables.

Date tables

A date table is a table of dates and other metadata about those dates. The relationship between facts tables and the date table allows end consumers to filter and compare data by time periods, such as months and years.

CALENDAR(<start_date>, <end_date>)

CALENDARAUTO([fiscal_year_end_month])

Role-playing dimensions

When two model tables have multiple relationships, it could be because your model has a role-playing dimension.

A role-playing dimension is a dimension that can filter related facts differently.

USERELATIONSHIP(<columnName1>,<columnName2>)