Power BI Interview Questions with Answers

Question: How would you write a DAX formula to calculate a running total that resets every year?
RunningTotal =
CALCULATE( SUM('Sales'[Amount]),
  FILTER( ALL('Sales'),
    'Sales'[Year] = EARLIER('Sales'[Year]) &&
    'Sales'[Date] <= EARLIER('Sales'[Date])))

Question: How would you manage and optimize Power BI reports that need to handle very large datasets (millions of rows)?
Solution:
1. Use DirectQuery mode if real-time data is needed.
2. Pre-aggregate data in the data source.
3. Use dataflows for preprocessing.
4. Implement incremental refresh.

Question: What steps would you take if a scheduled data refresh in Power BI fails?
Solution:
Check the Power BI service for error messages.
Verify data source connectivity and credentials.
Review gateway configuration.
Optimize and simplify the query.

Question: How would you create a report that dynamically updates based on user input or selections?
Solution: Use slicers and what-if parameters. Create dynamic measures using DAX that respond to user selections.

Question: How would you incorporate advanced analytics or machine learning models into Power BI?
Solution:
Use R or Python scripts in Power BI to apply advanced analytics.
Integrate with Azure Machine Learning to embed predictive models.
Use AI visuals like Key Influencers or Decomposition Tree.

Question: How would you integrate Power BI with other Microsoft services like SharePoint, Teams, or PowerApps?
Solution: Embed Power BI reports in SharePoint Online and Microsoft Teams. Use PowerApps to create custom forms that interact with Power BI data. Automate workflows with Power Automate.

Question: How to use if Parameters in Power BI?
Go to "Manage Parameters":
Navigate to the "Home" tab in the ribbon.
Click on "Manage Parameters" from the "External Tools" group.
Click on "New Parameter."
Enter a name for the parameter and select its data type (e.g., Text, Decimal Number, Integer, Date/Time).
Optionally, set the default value and any available values (for dropdown selection).

Question: What is the role of Power BI Paginated Reports and when are they used?
Solution: Power BI Paginated Reports (formerly SQL Server Reporting Services or SSRS) are used for pixel-perfect, printable, and paginated reports. They are typically used for operational and transactional reporting scenarios where precise formatting and layout control are required, such as invoices, statements, or regulatory reports.

Question: What are the options available for managing query parameters in Power Query Editor?
Solution: Power Query Editor allows users to define and manage query parameters to dynamically control data loading and transformation. Parameters can be created from values in the data source, entered manually, or generated from expressions, providing flexibility and reusability in query design.