Power BI is a business analytics solution a part of Power Apps developed by Microsoft that allows users to have interactive visualization of their data and share insights across their organization. This connects various data sources from which interactive reports and dashboards can be created. Here are some detailed answers to the most common Power BI interview questions categorized for freshers, intermediates, and those who have experience.
Common Power BI interview questions cover its definition, components, and differences from other tools like Tableau. Questions often focus on key functionalities such as Power Query, DAX, data modeling, reports, dashboards, and security features like row-level security and filters. Expected answers should demonstrate knowledge of the tool’s architecture, data connectivity, and practical application in a business intelligence context.
Basic and conceptual questions
- What is Power BI?
- A collection of software services, apps, and connectors that work together to turn your unrelated sources of data into coherent, visually immersive, and interactive insights.
- What are the major components of Power BI?
- Power BI Desktop (for designing reports), Power BI Service (SaaS cloud service for sharing and collaboration), and Power BI Mobile Apps (for accessing reports on devices).
- What is the difference between Power BI Desktop and Power BI Service?
- Power BI Desktop: A Windows application used to design and create reports by connecting to data, transforming it, and building a data model.
- Power BI Service: An online, cloud-based service where you publish reports from Desktop, create dashboards, and share them with others.
- What is DAX?
- Data Analysis Expressions (DAX) is a formula expression language used in Power BI, Analysis Services, and Power Pivot in Excel. It’s used to create calculated columns, measures, and tables.
Data transformation and modeling
- What is Power Query?
- A data transformation and data preparation engine that enables Power BI to connect to, transform, and load data from various sources before it’s modeled.
- What is Query Folding in Power BI?
- The process where Power BI translates queries written in M Language into a native query of the source database, allowing the database to perform the data transformation, which improves performance.
- What are the different connectivity modes in Power BI?
- Import: Data is loaded directly into the Power BI file.
- DirectQuery: Power BI sends queries directly to the data source to retrieve data as needed.
- Live Connection: Connects directly to certain models like SSAS or Power BI datasets.
- How do you define a relationship between two tables?
- You can create a relationship by dragging and dropping a column from one table to a corresponding column in another table in the Model view.
Reports and dashboards
- What is a Power BI Report?
- A collection of visuals, such as charts and tables, that are created in Power BI Desktop to represent data from a single dataset.
- What is a Power BI Dashboard?
- A single-page canvas, often called a canvas, that provides an at-a-glance view of key metrics. Dashboards are created in the Power BI Service and can pin visuals from one or more reports.
- What are Slicers?
- Visuals that act as filters, allowing users to interact with a report and filter the visuals to see specific data.
Security and sharing
- What is row-level security (RLS)?
- A feature that restricts user access to data at the row level. You can define roles in Power BI Desktop, and users who are part of those roles will only be able to see the data defined for that role.
- How do you share a Power BI report?
- You can share a report by publishing it to the Power BI Service and then using the “Share” option or by publishing an app.
- What is a Power BI Gateway?
- A gateway is required to enable scheduled data refresh for data sources that are not cloud-based (on-premises).
