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

Data modelling is the foundation of effective data analysis in Power BI. A well-structured model ensures faster performance, accurate calculations, and easier report building. This article breaks down everything you need to know—from SQL joins and Power BI relationships to schemas and practical implementation steps. What is Data Modelling? Data modelling is the process of organising data into tables and defining how those tables relate to each other so that analysis becomes meaningful and efficient. In Power BI, data modeling involves: Structuring tables (Fact and Dimension) Defining relationships between tables Optimizing performance and usability SQL Joins Explained (With Examples) Joins combine data from two or more tables based on a common column. Examples: Customers CustomerID Name 1 John 2 Mary 3 Alex Orders OrderID CustomerID 101 1 102 2 103 4 INNER JOIN Returns only matching records from both tables. Result: CustomerID Name OrderID 1 John 101 2 Mary 102 Use case: When you only