Power BI is one of the most sought-after business intelligence and data visualization tools. Whether you're a fresher or an experienced professional, preparing for Power BI interviews is crucial. This guide covers the top Power BI interview questions along with detailed answers to help you ace your interview.
Basic Power BI Interview Questions
1. What is Power BI?
Power BI is a business intelligence (BI) tool by Microsoft used for data analysis, visualization, and reporting. It allows users to connect to various data sources, create interactive reports, and share insights through dashboards.
2. What are the key components of Power BI?
Power BI consists of the following components:
Power Query – For data transformation and cleaning
Power Pivot – For data modeling and calculations
Power View – For data visualization
Power BI Service – Cloud-based platform for sharing reports
Power BI Report Server – For on-premises reporting
3. What are the different views in Power BI?
Power BI offers three main views:
Report View – For building visual reports
Data View – For inspecting and transforming data
Model View – For defining relationships between tables
Power BI Data Modeling and DAX Questions
4. What is DAX in Power BI?
DAX (Data Analysis Expressions) is a formula language used for creating custom calculations in Power BI.
Common DAX Functions:
SUM(Sales[Revenue]) – Adds up values in a column
CALCULATE(SUM(Sales[Amount]), Sales[Year] = 2025) – Filters data for specific conditions
IF(Sales[Revenue] > 10000, "High", "Low") – Applies conditional logic
5. What is the difference between Measures and Calculated Columns?
Feature Measure Calculated Column
Definition - A formula that calculates values dynamically A new column created based on existing data
Storage Stored in memory, recalculated dynamically Stored in the dataset
Example - SUM(Sales[Amount]) Sales Category = IF(Sales[Amount] > 5000, "High", "Low")
Power BI Data Connectivity and Performance Optimization
6. What is the difference between Import Mode and DirectQuery Mode?
Import Mode: Loads data into Power BI for faster performance.
DirectQuery Mode: Queries live data directly from the database, ensuring real-time updates.
7. What is Power BI Gateway?
Power BI Gateway is a bridge that connects on-premises data sources to the Power BI Service, enabling automatic data refresh.
8. How can you optimize Power BI performance?
Use Star Schema instead of Snowflake Schema
Reduce the number of visuals on a report page
Pre-aggregate large datasets
Optimize DAX expressions
Use query folding to push calculations back to the source
Advanced Power BI Interview Questions
9. What is Row-Level Security (RLS) in Power BI?
Row-Level Security (RLS) restricts data access based on user roles.
Example DAX filter for RLS:
- DAX - FILTER('Sales', Sales[Region] = USERPRINCIPALNAME())
- This ensures that users only see data for their assigned region.
10. How does Power BI handle relationships between tables?
Power BI uses Primary-Foreign key relationships with three types:
- One-to-One (1:1)
- One-to-Many (1:M) – Most commonly used
- Many-to-Many (M:M)
- Power BI Visualization and Reporting
11. What are the types of filters in Power BI?
- Visual Level Filters – Apply to a single chart or table
- Page Level Filters – Affect all visuals on a page
- Report Level Filters – Affect all report pages
- Drillthrough Filters – Navigate to a detailed view
- Top N Filters – Show the top N results
12. What is a Flipped Classroom model in Power BI training?
A Flipped Classroom model allows learners to study Power BI online at home through recorded lectures and use classroom time for hands-on exercises and discussions.
Scenario-Based Power BI Interview Questions
13. When should you use SUM() vs. SUMX()?
Function Usage
SUM() Aggregates an entire column
SUMX() Performs row-wise calculations before summing
Example:
DAX
TotalSales = SUM(Sales[Amount])
TotalSalesX = SUMX(Sales, Sales[Quantity] * Sales[Price])
SUMX() is useful when you need custom row-wise calculations before aggregation.
14. What is the difference between Star Schema and Snowflake Schema?
- Star Schema – Uses denormalized tables for better performance
- Snowflake Schema – Uses normalized tables for optimized storage
- What are the best practices for Power BI reporting?
- Use consistent color schemes and themes
- Keep dashboard layouts simple and intuitive
- Use tooltips to provide additional insights
- Minimize the use of complex DAX expressions in visuals
- Enable drill-through for detailed analysis
Conclusion
Power BI is a powerful tool for data analytics, business intelligence, and visualization. Preparing for a Power BI interview requires understanding its core concepts, data modeling, DAX, and performance optimization.
By mastering these Power BI interview questions, you'll be well-prepared to excel in your next Power BI job interview. 🚀
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