Context

Analysts moving from SQL to Power BI are often expected to explain how DAX works at a practical level. Interviewers usually want to know whether you understand how DAX differs from standard SQL aggregation logic.

Question

Explain how to use basic DAX in Power BI. Your answer should cover:

1. What DAX is and where it is used in Power BI
2. The difference between measures and calculated columns
3. How basic DAX functions such as SUM, COUNT, DIVIDE, and CALCULATE are used
4. How DAX evaluation context differs from a typical SQL query with GROUP BY

Scope Guidance

Keep the explanation at an interview level: define the core concepts clearly, show a few short examples, and connect them to SQL concepts the interviewer already knows. You do not need advanced time intelligence or complex filter propagation details, but you should be precise about when a measure recalculates versus when a calculated column is stored.