15 Power BI Interview Questions with Answers for freshers in 2025

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1?? What is Power BI?

Power BI is a business intelligence tool by Microsoft that helps in data visualization, reporting, and analytics. It allows users to connect to multiple data sources, transform data, create dashboards, and share insights.

2?? What are the key components of Power BI?

1. Power Query – Data transformation tool
2. Power Pivot – Data modeling and DAX calculations
3. Power View – Data visualization
4. Power Map – 3D geospatial analysis
5. Power BI Service – Cloud-based sharing and collaboration
6. Power BI Gateway – On-premises data connectivity
7. Power BI Report Server – On-premises report hosting

3?? What are the different types of Power BI views?

1. Report View – For creating visualizations
2. Data View – For viewing and cleaning data
3. Model View – For creating relationships and measures

4?? What is a DAX function?

DAX (Data Analysis Expressions) is a formula language used in Power BI for calculations and data analysis.

Examples include:

• SUM() – Adds values
• CALCULATE() – Modifies filter context
• IF() – Conditional logic

5?? What are measures and calculated columns in Power BI?

• Measure – A dynamic calculation applied to a dataset (e.g., SUM of sales).
• Calculated Column – A static column added to a table (e.g., Sales Category = IF(Sales > 5000, "High", "Low")).

6?? What is the difference between Power BI Desktop and Power BI Service?

• Power BI Desktop – Used for designing and developing reports.
• Power BI Service – Cloud-based platform for publishing, sharing, and collaborating on reports.

7?? What is Power BI Gateway?

A Power BI Gateway is used to connect on-premises data sources with the Power BI Service for real-time data refresh.

8?? What is the difference between Star and Snowflake Schema?

• Star Schema – A single fact table connected to multiple dimension tables (simpler, faster).
• Snowflake Schema – A fact table with normalized dimension tables (complex, optimized storage).

9?? How does Power BI handle relationships between tables?

Power BI uses primary-foreign key relationships to connect tables.

Relationships can be:

• One-to-One (1:1)
• One-to-Many (1:M) (most common)
• Many-to-Many (M:M)

?? What are the types of Power BI filters?

1. Visual Level Filters – Apply to a single visualization
2. Page Level Filters – Apply to an entire report page
3. Report Level Filters – Apply to the entire report
4. Drillthrough Filters – Navigate to a specific detail page
5. Top N Filters – Show top N values

1??1?? What is the difference between DirectQuery and Import Mode?

• Import Mode – Data is loaded into Power BI (faster but consumes memory).
• DirectQuery Mode – Queries live data from the source (real-time but slower).

1??2?? What is row-level security (RLS) in Power BI?

Row-Level Security (RLS) restricts data access based on user roles.

Example:

DAX -- [Region] = USERPRINCIPALNAME()        

This ensures users can only see data relevant to their role.

1??3?? What is the use of CALCULATE() in DAX?

CALCULATE() modifies filter context in DAX expressions.

Example:

DAX -- TotalSales2025 = CALCULATE(SUM(Sales[Amount]), Sales[Year] = 2025)        

This calculates sales only for the year 2025.

1??4?? What is the difference between SUM() and SUMX()?

• SUM() – Aggregates a column.
• SUMX() – Performs row-wise calculation before summing.

1??5?? How can you optimize Power BI performance?

1. Use Star Schema instead of Snowflake.
2. Reduce the number of visuals on a report page.
3. Use aggregations and summarization.
4. Avoid complex DAX calculations in visuals.
5. Optimize data model relationships.

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