Top 50 Power BI Interview Questions with Answers

1. What is Power BI?

Power BI is a Microsoft business analytics tool that enables users to connect to multiple data sources, transform and model data, and create interactive reports and dashboards for data-driven decision making.

2. Explain the key components of Power BI.

The main components are:

⦁ Power Query for data extraction and transformation.

⦁ Power Pivot for data modeling and relationships.

⦁ Power View for interactive visualizations.

⦁ Power BI Service for publishing and sharing reports.

⦁ Power BI Mobile for accessing reports on mobile devices.

3. Differentiate between Power BI Desktop, Service, and Mobile.

⦁ Desktop: The primary application for building reports and models.

⦁ Service: Cloud-based platform for publishing, sharing, and collaboration.

⦁ Mobile: Apps for viewing reports and dashboards on mobile devices.

4. What are the different types of data sources in Power BI?

Power BI connects to a wide range of sources: files (Excel, CSV), databases (SQL Server, Oracle), cloud sources (Azure, Salesforce), online services, and web APIs.

5. Explain the Get Data process in Power BI.

“Get Data” is the process to connect and import data into Power BI from various sources using connectors, enabling users to load and prepare data for analysis.

6. What is Power Query Editor?

Power Query Editor is a graphical interface in Power BI for data transformation and cleansing, allowing users to filter, merge, pivot, and shape data before loading it into the model.

7. How do you clean and transform data in Power Query?

By applying transformations like removing duplicates, filtering rows, changing data types, splitting columns, merging queries, and adding calculated columns using the intuitive UI or M language.

8. What are the different data transformations available in Power Query?

Common transformations include filtering rows, sorting, pivot/unpivot columns, splitting columns, replacing values, aggregations, and adding custom columns.

9. What is the M language in Power BI?

M is the functional programming language behind Power Query, used for building advanced data transformation scripts beyond the UI capabilities.

10. Explain the concept of data modeling in Power BI.

Data modeling is organizing data tables, defining relationships, setting cardinality and cross-filter directions, and creating calculated columns and measures to enable efficient and accurate data analysis.

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11. What are relationships in Power BI?

Relationships define how data tables are connected through common columns (keys), enabling you to combine and analyze related data effectively across tables.

12. What are the different types of relationships in Power BI?

⦁ One-to-many: One row in table A relates to multiple rows in table B.

⦁ One-to-one: One row in table A relates to exactly one row in table B.

⦁ Many-to-many: Multiple rows in one table relate to multiple rows in another, supported via bridge tables.

13. What is cardinality in Power BI?

Cardinality refers to the uniqueness of data values in a column that participates in a relationship, e.g., one-to-many cardinality means a unique key on one side and non-unique on the other.

14. What is cross-filter direction in Power BI?

It determines how filters flow between related tables:

⦁ Single: Filters flow in one direction.

⦁ Both: Filters flow both ways, enabling bi-directional filtering in reports.

15. How do you create calculated columns and measures?

Use DAX formulas in Power BI Desktop:

⦁ Calculated columns add extra columns at the row level stored in the data model.

⦁ Measures are calculations performed dynamically on aggregated data during report interactions.

16. What is DAX?

DAX (Data Analysis Expressions) is a formula language tailored for Power BI for creating custom calculations like calculated columns, measures, filtering, and aggregations within the data model.

17. Explain the difference between calculated columns and measures.

⦁ Calculated columns compute values row by row when data is loaded and store them.

⦁ Measures compute results on-the-fly, aggregate data dynamically depending on the filter context.

18. List some common DAX functions.

Common functions include:

⦁ SUM(), AVERAGE(), COUNT(), RELATED(), CALCULATE(), FILTER(), IF(), ALL(), VALUES().

19. What is the CALCULATE function in DAX?

CALCULATE() modifies the filter context of a calculation, enabling complex conditional logic and dynamic aggregation based on filters.

20. How do you use variables in DAX?

Variables store intermediate values in a DAX formula for better readability and performance, declared using VAR and returned using RETURN.

21. What are the different types of visuals in Power BI?

Power BI offers various visuals like bar charts, column charts, line charts, pie charts, scatter plots, maps, tables, matrices, cards, gauges, and custom visuals that extend functionality.

22. How do you create interactive dashboards in Power BI?

By combining multiple visuals, slicers, filters, drill-throughs, and bookmarks to allow users to explore data dynamically and gain insights across different levels.

23. Explain the use of slicers in Power BI.

Slicers are visual filters that let users filter data interactively on reports; they improve user experience by enabling quick data segment exploration.

24. What are filters in Power BI?

Filters restrict data displayed in visuals or pages. They can be applied at the visual level, page level, or report level, depending on the scope.

25. How do you use bookmarks in Power BI?

Bookmarks capture the current report state—filters, slicers, visuals—for use in storytelling, navigation, or creating customized report views.

26. What is the Power BI Service?

A cloud-based platform where users publish reports, create dashboards, share content, collaborate, schedule data refresh, and manage workspaces.

27. How do you publish reports to the Power BI Service?

From Power BI Desktop, click “Publish” to upload reports to your workspace in Power BI Service for sharing and scheduling refresh.

28. How do you create dashboards in the Power BI Service?

Dashboards are created by pinning visuals or entire report pages from published reports to a dashboard canvas in the Power BI Service.

29. How do you share reports and dashboards in Power BI?

By sharing directly with users or groups, embedding in apps, or creating content packs in workspaces with appropriate permissions.

30. What are workspaces in Power BI?

Workspaces are collaborative environments in Power BI Service where teams develop, manage, and distribute reports and dashboards.

31. Explain the role of gateways in Power BI.

Gateways connect on-premises data sources to the Power BI Service securely, enabling scheduled data refresh without moving data to the cloud.

32. How do you schedule data refresh in Power BI?

In the Power BI Service, configure refresh frequency (daily/weekly), time, and credentials to automate dataset updates, using gateways if on-premises sources are involved.

33. What is Row-Level Security (RLS) in Power BI?

RLS restricts data access for users based on roles by filtering rows dynamically, ensuring users see only data relevant to them.

34. How do you implement RLS in Power BI?

Define roles and DAX filters in Power BI Desktop’s Modeling tab, then assign users to these roles in Power BI Service.

35. What are Power BI apps?

Apps are packaged collections of dashboards, reports, and datasets distributed to wider audiences for easier consumption and governance.

36. What are dataflows in Power BI?

Dataflows allow ETL (extract, transform, load) processes to be created in the cloud, reusing data preparation logic across multiple datasets.

37. How do you use parameters in Power BI?

Parameters enable dynamic input values for queries or data transformations, making reports more flexible (e.g., changing data source or filter values).

38. What are custom visuals in Power BI?

User-developed or marketplace visuals that extend standard Power BI visuals with specialized charts and unique features.

39. How do you import custom visuals into Power BI?

Download visual (.pbiviz) files or add from AppSource marketplace directly inside Power BI Desktop or Service.

40. Explain performance optimization techniques in Power BI.

Use star schema modeling, prefer measures over calculated columns, limit visuals per page, optimize data queries, enable query reduction, and apply aggregations.

41. What is the difference between import and direct query mode?

⦁ Import: Data is loaded into Power BI’s in-memory engine for fast performance.

⦁ DirectQuery: Queries data live from the source without importing, good for real-time data but slower response.

42. When should you use direct query mode?

Use DirectQuery when data is very large or constantly changing, requiring real-time or near real-time access without importing all data.

43. How do you connect to cloud data sources in Power BI?

Power BI supports built-in connectors for cloud sources like Azure SQL Database, Azure Data Lake, Salesforce, Google Analytics, and others, allowing secure and direct connections.

44. What are the advantages of using Power BI?

It offers user-friendly interfaces, connectivity to many data sources, powerful data modeling with DAX, interactive reports/dashboards, cloud collaboration, and scalability.

45. How do you handle errors in Power BI?

Use Power Query error handling features, validate data before loading, apply try/otherwise steps in M language, and monitor refresh logs to troubleshoot issues.

46. What are the limitations of Power BI?

Limitations include dataset size limits (1GB for free, larger with Premium), limited custom visual flexibility, dependency on the internet for Service, and data refresh frequency limits.

47. Explain Power BI Embedded.

Power BI Embedded allows developers to embed Power BI reports and dashboards into custom applications, providing analytics and visualization capabilities within third-party apps.

48. What is Power BI Report Server?

An on-premises solution to host, publish, and manage Power BI reports within a company’s own infrastructure, helping with compliance and data security.

49. How do you use Power BI with Azure?

Integrate Power BI with Azure services like Azure Synapse, Azure Data Lake, and Azure Machine Learning for enhanced data processing, advanced analytics, and scalable storage.

50. What are the latest features of Power BI?

Includes enhanced AI visuals, improved dataflows, new DAX functions, field parameters for dynamic axis, new connectors, performance boosts, and expanded deployment options.

Top 50 Power BI Interview Questions with Answers