Top 10 Power BI interview questions for freshers in 2025
1. What is Power BI? Explain its key components.
Power BI is a business analytics tool by Microsoft for visualizing data and sharing insights. Key components:
- Power BI Desktop (for report creation)
- Power BI Service (cloud-based sharing)
- Power BI Mobile (mobile access)
- DAX (Data Analysis Expressions) (formula language)
2. What is Power Query, and how is it used in Power BI?
Power Query is the ETL (Extract, Transform, Load) tool in Power BI for:
- Cleaning data (removing duplicates, fixing errors)
- Merging datasets
- Transforming data (splitting columns, pivoting)
3. Explain the difference between “Import” and “DirectQuery” modes.
- Import Mode: Data is loaded into Power BI’s memory (fast but limited by dataset size).
- DirectQuery: Data stays in the source (real-time but slower performance).
4. What is DAX? Give an example of a common DAX function.
DAX is Power BI’s formula language for calculations.
Example:
Total Sales = SUM(Sales[Amount])
Other functions: CALCULATE()
, FILTER()
, RELATED()
.
5. How do you create a relationship between tables in Power BI?
- Go to “Model View” → Drag a field from one table to another.
- Set cardinality (e.g., One-to-Many) and cross-filter direction.
6. What is a “measure” vs. a “calculated column”?
- Measure: Dynamic calculation (e.g.,
Total Sales = SUM(Sales[Amount])
). - Calculated Column: Static, row-level calculation (e.g.,
Profit = [Revenue] - [Cost]
).
7. How would you optimize a slow Power BI report?
- Use DirectQuery for large datasets.
- Limit visuals on a single page.
- Avoid complex DAX.
- Use aggregations or incremental refresh.
8. What is Row-Level Security (RLS)?
RLS restricts data access based on user roles. Example: A salesperson only sees their region’s data.
9. Explain “drill-through” in Power BI.
A feature to navigate from summary data (e.g., country sales) to details (e.g., city-level sales) by clicking a data point.
10. How do you share a Power BI report with stakeholders?
- Publish to Power BI Service → Share via link or workspace.
- Export to PDF/PPT (static) or use Power BI Apps (interactive).
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