Hello everyone! I’m on a journey to learn advanced features of Power BI’s DAX language. One pivotal concept that I’ve discovered is the use of variables with the VAR keyword. Understanding this feature will not only make your code cleaner and easier to read but can also significantly improve performance. So let’s delve into this fascinating aspect of DAX!

VAR in DAX: The Syntax

The syntax for declaring a variable in DAX is straightforward:

VAR <Variable_Name> = <Expression>

RETURN <Result_Expression>

Once a variable is defined using VAR, you can reference it multiple times in the RETURN statement, thereby making your code more efficient and easier to manage.

Example 1: Basic Variable Usage

Imagine you need to calculate the net profit for a set of transactions. Without variables, you might find yourself repeatedly calculating the sum of revenues and costs, which could lead to messy and inefficient code. Here’s how you can simplify the task using VAR:

In this example, TotalRevenue and TotalCost are variables that hold the sum of the Revenue and Cost columns, respectively. The RETURN statement then uses these variables to calculate the net profit.

Example 2: Female Ratio Calculation

In this example, we will define multiple variables (VAR) and use them later in the same DAX calculation to find the ratio of orders made by females.

Notice how each variable has a clear, self-explanatory name, and how we use these variables to calculate the Female_Ratio. This makes the code easier to understand and debug if needed.

Benefits of Using Variables

1.Readability: Using variables can substantially enhance the readability of your code. Clear variable names and reduced repetition make it easier for others (or yourself at a later date) to understand your calculations.

2.Performance: A variable is calculated only once, but you can use it multiple times in your expressions. This feature can contribute to better query performance.

3.Debugging: If something goes wrong, variables make it easier to debug your DAX code. You can evaluate each variable independently, making it simpler to identify where an issue might be occurring.

That’s it for this blog! Catch you in the next post.


The Data School
Author: The Data School