Learn Power BI DAX in 30 minutes
What is DAX in POwer BI?
Data Analysis Expressions (DAX) in power BI is a set of functions, operators, and constants that can be used in a formula, or expression, to calculate and return one or more values. Stated more simply, DAX helps you create new information from data already in your model.
Benefit of using DAX
It’s quite easy to create a new Power BI Desktop file and import some data into it. You can even create reports that show valuable insights without using any DAX formulas at all. But, for instance if you need to analyze growth percentage across product categories and for different date ranges Or if you need to calculate year-over-year growth compared to market trends, you need DAX. DAX formulas provide capabilities to accomplish such type of complex formula and many other important capabilities as well. Learning how to create effective DAX formulas will help you get the most out of your data. When you get the information you need, you can begin to solve real business problems that affect your bottom line.
Who can learn DAX?
Whoever are already being familiar with creating formulas in Microsoft Excel can easily learn DAX. That knowledge will be helpful in understanding DAX.
We’re going to focus on understanding DAX formulas used in calculations, more specifically, in measures and calculated columns. One should already be familiar with Power BI Desktop, importing data, adding fields to a report, and you should also be familiar with fundamental concepts of Measures and Calculated columns.
Let’s look at a simple DAX formula for a measure.
This formula includes the following syntax elements:
A. The measure name Total Sales.
B. The equals sign operator (=) indicates the beginning of the formula. When calculated, it will return a result.
C. The DAX function SUM adds up all of the numbers in the Sales[SalesAmount] column. You’ll learn more about functions later.
D. Parenthesis () surround an expression containing one or more arguments. All functions require at least one argument. An argument passes a value to a function.
E. The referenced table Sales.
F. The referenced column [SalesAmount] in the Sales table. With this argument, the SUM function knows on which column to aggregate a SUM.
When added to a report, this measure calculates and returns values by summing up sales amounts for each of the other fields.