Top powerBi interview questions for freshers 2024
Top powerBi interview questions for freshers 2024
Top Power BI Interview Questions and Answers for Freshers
1. What is Power BI?
Answer: Power BI is a business analytics service by Microsoft. It provides interactive visualizations and business intelligence capabilities with an interface simple enough for end users to create their own reports and dashboards.
2. What are the main components of Power BI?
Answer:
- Power BI Desktop: A Windows application for creating reports.
- Power BI Service: An online SaaS (Software as a Service) for sharing and publishing reports.
- Power BI Mobile Apps: Mobile applications for viewing reports and dashboards on the go.
- Power BI Gateway: Bridges data connectivity and secure transfer between Power BI and on-premises data sources.
- Power BI Report Server: An on-premises report server for hosting Power BI reports.
3. What are the different types of refreshes in Power BI?
Answer:
- Package Refresh: Refreshes the dataset by republishing the file from Power BI Desktop.
- Model/Data Refresh: Refreshes the dataset by updating the data with the source data.
- Tile Refresh: Updates the dashboard tiles with the latest data from the reports.
- Visual Container Refresh: Refreshes the visuals in the report or dashboard.
4. What are content packs in Power BI?
Answer: Content packs are pre-packaged Power BI dashboards, reports, and datasets that can be shared with other users or organizations. They provide a quick way to distribute a collection of related Power BI content.
5. What is DAX in Power BI?
Answer: DAX (Data Analysis Expressions) is a formula language used in Power BI, Power Pivot, and SQL Server Analysis Services to define custom calculations and aggregations in the data model.
6. What are calculated columns in Power BI?
Answer: Calculated columns are DAX expressions that are computed during the data refresh process and stored in the data model. They are useful for adding new data columns based on existing data.
7. What are the different types of filters in Power BI?
Answer:
- Report Level Filters: Apply to the entire report.
- Page Level Filters: Apply to a specific page within the report.
- Visual Level Filters: Apply to a specific visual within the report.
8. What are Power BI templates?
Answer: Power BI templates (.pbit files) are files that contain the report definition, including visuals, queries, and data model schema, but do not include the data. They are used to share report designs without sharing the underlying data.
9. How does Power BI handle security?
Answer: Power BI handles security through roles and row-level security (RLS). RLS allows you to restrict data access for specific users based on their roles within the organization.
10. What is the use of Power Query in Power BI?
Answer: Power Query is a data connection technology that enables you to discover, connect, combine, and refine data across a wide variety of sources. It is used for data transformation and preparation before it is loaded into the data model.
11. Explain the difference between a dashboard and a report in Power BI.
Answer:
- Dashboard: A single-page, often called a canvas, that uses visualizations to tell a story. It can be made up of visuals from multiple reports and datasets.
- Report: A multi-page document that contains multiple visualizations, often from a single dataset, used to present data insights.
12. What is Power Pivot in Power BI?
Answer: Power Pivot is a data modeling technology that allows you to create data models, establish relationships, and create calculations. It is integrated into Power BI for advanced data analysis and is also available in Excel.
13. What is a Power BI Gateway?
Answer: A Power BI Gateway is a software component that facilitates the secure transfer of data between on-premises data sources and Power BI Service. It allows for scheduled data refresh and live queries.
14. What is the Power BI Service?
Answer: Power BI Service is a cloud-based service that allows users to share, collaborate, and publish Power BI reports and dashboards. It enables users to access their Power BI content from anywhere with internet connectivity.
15. What is drill-through in Power BI?
Answer: Drill-through allows users to navigate from one report page to another, focusing on specific details related to the data. It helps in exploring data by drilling into details without cluttering the primary report page.
16. What is the difference between direct query and import mode in Power BI?
Answer:
- Import Mode: Data is imported and stored in the Power BI model. It allows for fast query performance but may have dataset size limitations.
- Direct Query Mode: Data remains in the source system and queries are sent in real-time. It allows for real-time data access but may be slower due to query execution on the source system.
17. What is the role of Power BI Desktop?
Answer: Power BI Desktop is a Windows application that is used to create reports and data visualizations. It is a comprehensive tool for data preparation, data modeling, and creating interactive reports.
18. What are custom visuals in Power BI?
Answer: Custom visuals are user-defined visuals that can be created using the Power BI Visuals SDK. They can be used to extend the capabilities of Power BI with bespoke visualizations that meet specific business needs.
19. What is the purpose of bookmarks in Power BI?
Answer: Bookmarks capture the current state of a report page, including filters and visuals. They are used to create navigation buttons, tell data stories, and create presentations within Power BI reports.
20. What is a slicer in Power BI?
Answer: A slicer is a visual filter that allows users to select values from a list and dynamically filter data in other visuals on the report page.
21. Explain the difference between Power BI Pro and Power BI Premium.
Answer:
- Power BI Pro: A subscription license that allows users to share, collaborate, and publish content with other Power BI Pro users.
- Power BI Premium: A capacity-based license that provides dedicated resources and additional features such as paginated reports, larger dataset sizes, and enhanced performance.
22. What is the purpose of DAX functions in Power BI?
Answer: DAX functions are used for data manipulation and calculations in Power BI. They help in creating custom aggregations, calculated columns, measures, and complex business logic.
23. What is Q&A in Power BI?
Answer: Q&A is a natural language querying feature in Power BI that allows users to ask questions about their data in plain language and get answers in the form of visualizations.
24. What is the purpose of the Merge and Append queries in Power BI?
Answer:
- Merge Queries: Combines two queries into one based on a common column (similar to SQL joins).
- Append Queries: Combines rows from two or more queries into a single query (similar to SQL UNION).
25. What is Power BI Embedded?
Answer: Power BI Embedded is a service that allows developers to embed Power BI reports and dashboards into web applications using APIs and client libraries.
26. How can you share a Power BI report with others?
Answer: Reports can be shared through the Power BI Service by publishing the report to a workspace, sharing a link, embedding it in a website or application, or using Power BI apps.
27. What is the role of Power BI administration?
Answer: Power BI administration involves managing user access, monitoring usage, configuring tenant settings, and ensuring compliance with organizational policies. Admins use the Power BI Admin Portal for these tasks.
28. What is the use of the ALLEXCEPT function in DAX?
Answer: The ALLEXCEPT function in DAX removes all filters from a table except for the filters applied to the specified columns. It is useful for creating measures that need to ignore certain filters.
29. What are some best practices for designing Power BI reports?
Answer: Best practices include:
- Keeping the design simple and intuitive.
- Using consistent color schemes and themes.
- Avoiding clutter by using appropriate visuals.
- Optimizing for performance.
- Ensuring data accuracy and relevance.
- Providing clear and actionable insights.
30. What is Power BI’s REST API?
Answer: Power BI’s REST API allows developers to programmatically interact with Power BI Service. It provides endpoints for embedding, managing datasets, reports, dashboards, and other Power BI artifacts.
31. How do you handle large datasets in Power BI?
Answer: Handling large datasets can be done by using techniques such as:
- Incremental data refresh.
- Using DirectQuery mode.
- Optimizing data models.
- Aggregating data.
- Using Power BI Premium for larger dataset sizes.
32. What is the purpose of CALCULATE function in DAX?
Answer: The CALCULATE function evaluates an expression in a modified filter context. It is used to create measures with custom filters and complex calculations.
33. What is row-level security (RLS) in Power BI?
Answer: RLS allows you to restrict data access for users based on their roles. It is implemented by defining roles and DAX filters that control which data rows users can see.
34. What are Power BI Dataflows?
Answer: Power BI Dataflows are a self-service data preparation tool that allows users to create and manage ETL (Extract, Transform, Load) processes in the Power BI Service. They help in reusing data transformation logic across multiple datasets and reports.
35. What is the use of SUMX function in DAX?
Answer: The SUMX function iterates over a table, evaluates an expression for each row, and returns the sum of the expression results. It is used for row-wise calculations.
36. What is the difference between ALL and ALLSELECTED in DAX?
Answer:
- ALL: Removes all filters from the specified table or column.
- ALLSELECTED: Removes filters only from the visual context but retains filters from slicers and other visuals.
37. What are some key features of Power BI?
Answer: Key features include:
- Data connectivity and integration with various sources.
- Interactive reports and dashboards.
- Natural language Q&A.
- Custom visualizations.
- Real-time streaming data.
- AI and machine learning integration.
- Mobile accessibility.
- Secure data sharing and collaboration.
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