Preparing for a Power BI interview can feel overwhelming, whether you’re just starting your data analytics journey or aiming for an advanced BI developer role. This guide, From Beginner to Pro Power BI Interview Questions & Answers, is designed to help you succeed. We cover everything from basic concepts like dashboards, data modeling, and DAX functions to advanced topics such as performance tuning, Direct Query vs Import, and integrating AI features. Alongside the right Power BI training, these practical answers and real-world examples will give you the confidence to tackle any Power BI interview and showcase your expertise effectively.
1. What is Power BI and how does it differ from Excel?
How to answer: Define Power BI, highlight that it’s a business intelligence tool for interactive visualizations, explain differences with Excel (dynamic reports, automation, data modeling).
Example: In a sales dashboard, I used Power BI to connect directly to a SQL database, ensuring real-time updates, unlike Excel where I had to refresh manually.
2. Difference between Power BI Desktop and Power BI Service?
How to answer: Explain that Desktop is for report creation, Service is for sharing and collaboration in the cloud.
Example: I designed a marketing performance report in Power BI Desktop and then published it to Power BI Service for the team to view live updates.
3. What are Power BI Dataflows?
How to answer: Define dataflows as reusable ETL processes built in Power BI Service to prepare and transform data.
Example: In a customer analytics project, I used a dataflow to clean CRM data once, which multiple reports could then use.
4. What is a Dataset in Power BI?
How to answer: A dataset is a collection of data loaded or connected to Power BI, used to build reports.
Example: For sales tracking, I used a dataset from both an Excel file and an SQL database, enabling blended insights.
5. Explain the difference between Report and Dashboard in Power BI.
How to answer: Reports are multi-page and detailed, dashboards are single-page summaries with tiles from multiple reports.
Example: I created a multi-page financial report and then built a one-page dashboard for executives to see key KPIs.
6. What are Measures and Calculated Columns in Power BI?
How to answer: Measures are calculations done on aggregated data; calculated columns add new fields to data tables.
Example: I created a measure for Total Profit Margin and a calculated column for Sales Category in my retail dashboard.
7. What is DAX in Power BI?
How to answer: DAX (Data Analysis Expressions) is a formula language for creating custom calculations in Power BI.
Example: Using DAX, I created a Year-to-Date Sales measure to compare current performance with last year’s.
8. What are Power BI Gateways?
How to answer: Gateways connect on-premises data sources to Power BI Service for scheduled refreshes.
Example: In a manufacturing report, I set up a gateway to refresh ERP data automatically every morning.
9. What is Row-Level Security (RLS) in Power BI?
How to answer: RLS restricts data access for certain users based on filters.
Example: For a regional sales report, I applied RLS so each manager only saw data for their territory.
10. What is the difference between DirectQuery and Import Mode?
How to answer: Import Mode loads data into Power BI; DirectQuery queries data from the source in real-time.
Example: For real-time inventory tracking, I used DirectQuery to pull live data from the warehouse database.
11. How do you optimize Power BI performance?
How to answer: Mention reducing dataset size, using star schema, optimizing DAX, and enabling query folding.
Example: I replaced calculated columns with measures and filtered unused columns, reducing report load time by 40%.
12. What is the Power Query Editor in Power BI?
How to answer: A tool to connect, transform, and clean data before loading into Power BI.
Example: I used Power Query to remove null values and standardize date formats before visualizing sales trends.
13. How do you create relationships between tables in Power BI?
How to answer: By defining primary and foreign keys in the model view for accurate joins.
Example: I linked Orders and Customers tables on CustomerID to analyze repeat purchase patterns.
14. What is the difference between a Star Schema and Snowflake Schema in Power BI?
How to answer: Star schema has denormalized dimensions for performance; snowflake schema normalizes data.
Example: I used a star schema in a sales model for faster dashboard load times.
15. What is the use of Bookmarks in Power BI?
How to answer: Bookmarks save report states for navigation or storytelling.
Example: I created bookmarks to switch between quarterly and annual sales views in one click.
16. What is a KPI Visual in Power BI?
How to answer: A KPI visual tracks performance against a target with indicators.
Example: I used a KPI visual to monitor whether daily website visits met the marketing team’s target.
17. What is Drillthrough in Power BI?
How to answer: Drillthrough allows users to click on data points to see detailed pages.
Example: In a sales dashboard, clicking on a product category opened a detailed regional sales breakdown.
18. How do you handle missing or null values in Power BI?
How to answer: Through Power Query transformations like replacing, removing, or imputing values.
Example: In a customer demographics dataset, I replaced missing age data with median values.
19. What are Quick Measures in Power BI?
How to answer: Pre-built DAX formulas for common calculations.
Example: I used a quick measure to calculate year-over-year sales growth without writing complex DAX.
20. What are Custom Visuals in Power BI?
How to answer: Visualizations from the marketplace or created with custom code.
Example: I added a heatmap custom visual to highlight sales hotspots on a geographic map.
21. What is Drilldown in Power BI Charts?
How to answer: Drilldown lets users explore data from summary to detailed levels.
Example: Clicking on yearly sales drilled down to quarterly and monthly figures.
22. What is the difference between All Filters and Visual-Level Filters in Power BI?
How to answer: All filters affect the whole report; visual-level filters affect only specific visuals.
Example: I used a visual-level filter to show only high-value customers in one chart without affecting others.
23. What is the difference between Append Queries and Merge Queries?
How to answer: Append stacks datasets vertically; merge joins them horizontally.
Example: I appended monthly sales CSV files and merged them with product details from the database.
24. What is a Paginated Report in Power BI?
How to answer: A detailed, printable report optimized for pixel-perfect layouts.
Example: I created a paginated invoice report for finance that could be exported to PDF.
25. What is Q&A in Power BI?
How to answer: Q&A lets users type natural language questions to generate visuals automatically.
Example: Typing “Total Sales by Region for 2024” instantly produced a map visual in my dashboard.
