Unlock the full potential of Power Query M language by mastering Custom Functions! In this comprehensive tutorial, you’ll learn exactly what a Power Query M Custom Function is—a reusable block of M code that simplifies your data transformations, improves reusability, and makes your queries much easier to maintain. We’ll walk through a practical, real-world example: calculating complex sales commissions for different salespeople based on their sales performance and even special weekend rates. Discover how to create a blank query, structure your M code with parameters (including optional ones!), define output data types, and implement conditional logic using if/then/else statements to dynamically determine commission rates. This is a must-watch for anyone looking to go beyond basic Power Query transformations and build robust, scalable data models.
We’ll start by importing data from an Excel file into the Power Query Editor, and then dive deep into the Advanced Query Editor to write our custom M function from scratch. You’ll learn how to set up parameters for Sales Amount, Sales Target, Low Rate, High Rate, Day of Week Name, and an optional logical parameter for Weekend Rate Policy. Once the function is built, we’ll show you how to apply it to your dataset using a Custom Column, first converting dates into day names, then calculating the precise commission rate for every single sales record. Finally, we’ll load the transformed data into the data pane and build a simple yet powerful Power BI dashboard with line and column charts to visualize daily sales, sales by person, and the total commission earned, ensuring all data types are correctly formatted for aggregation. Don’t forget to like, subscribe, and hit the notification bell for more advanced Power Query and data transformation tips!
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