What is DAX and how to use it in Power BI?

We all know that Power BI is an incredibly powerful and interactive data visualisation tool.  Regular users of Power BI often like to take their skills and modelling abilities to the next level by learning how to write DAX on their own, which stands for Data Analysis Expressions.  DAX is the formula language used in Power BI and is also used in other Microsoft programs such as Power Pivot.  Read on for a quick lesson into what DAX is and how you can use within Power BI.

What is DAX?

DAX is a functional programming language, meaning the full executed code is contained inside a function.  It’s designed to work with tables, so the language has only two primary data types:  Numeric (includes integers, decimals and currency), and Other (includes strings and binary objects).  Because DAX uses operator overloading, it means users can mix data types in their calculations and their results will change automatically based on what type of data was used.

DAX calculations and functions

There are two primary calculations you can create using DAX, which are calculated columns and calculated measures.

Calculated columns are useful when you want to slice or filter on the value, or when you want a calculation for every row in your table.  On the other hand, calculated measures are useful when you want to calculate a percentage or ratio or you need complex aggregations.

There are many functions available within DAX to help you shape, form and analyse your data.  The functions within DAX are often grouped into categories such as aggregation functions, counting functions, logical functions, information functions, text functions and date functions.

Learning to write DAX functions and understand expressions is key for users who want to build on their data analysis skills.  With even a one-day course, users can learn to create complex expressions, manage and create DAX and learn methods to optimise their expressions.

To start your journey in Power BI, see our courses . To learn more about DAX and how to best use it for your business, you can check out our DAX course .