Learn when to use Power BI DirectQuery, how to improve report performance, and which modeling, DAX, source-design, and visual mistakes to avoid.

Hook: If your model “mysteriously” changes numbers, breaks relationships, or sorts months alphabetically—blame data types. What we’ll cover: where to define types (and why), the safest order of operations across the ETL chain, Power Query vs. Model vs. Table View, special cases (DirectQuery, currency, duration), and concrete, copy-paste examples. 1) Why data types matter (and where they live) Power Query (PQ): Data shaping stage. Types here affect folding, transformations

Power BI Service is Microsoft’s cloud-based platform for sharing, collaborating on, and interacting with data and reports. Think of it as the online companion to Power BI Desktop. While Power BI Desktop (a free Windows app) is where analysts build data models and design reports, the Power BI Service ( app.powerbi.com ) is where you share and consume those reports, dashboards, and apps with others. In practice, you’d do your data cleanup, modelling, and report design in Desk