Understanding Data Modeling in Power BI: Joins, Relationships, and Schemas Explained.

If you’ve ever felt confused about joins vs relationships, or why your Power BI report is giving incorrect totals, this is where data modeling comes in. This guide breaks it down simply, with real-world examples and practical steps inside Power BI. 1. What is Data Modeling? Data modeling is how you structure your data so Power BI can: Understand relationships between tables Aggregate data correctly Perform fast and accurate calculations Think of it like this: Data modeling = organizing your data into a clean, logical system before analysis. 2. Joins in Power BI (Power Query) Joins happen before data is loaded, inside Power Query. They physically combine tables. Where to create joins: Go to Home → Transform Data Open Power Query Select a table Click Merge Queries Choose another table and matching column(s) Select join type Types of Joins (with real-life examples) 1. INNER JOIN Returns only matching records. Example: Customers table Orders table Only customers who placed orders appear. C