Unlock the secrets to acing your Power BI interviews with our comprehensive guide! Whether you're a seasoned data analyst or just starting your journey in business intelligence, our blog on CodersDaily.in has got you covered with the top 50 interview questions you need to know in 2024. From Power BI basics to advanced DAX functions, data visualisation best practices, and tackling real-world challenges, we provide concise explanations and solutions to help you showcase your expertise and land your dream job. Dive into the world of Power BI and elevate your interview game today!
Power BI Basics:
- What is Power BI?
- Power BI is a business analytics tool by Microsoft used for analyzing data and sharing insights.
- What are the components of Power BI?
- Power BI Desktop, Power BI Service (cloud service), Power BI Mobile, Power BI Gateway.
- Explain the difference between Power BI Desktop and Power BI Service.
- Power BI Desktop is used for creating reports and dashboards locally, while Power BI Service is a cloud-based platform for sharing and collaborating on reports.
- How can you publish reports from Power BI Desktop to Power BI Service?
- Reports can be published from Power BI Desktop to Power BI Service by clicking on the "Publish" button in the toolbar and signing in with your Power BI account.
- What is a Power BI Gateway, and when is it used?
- Power BI Gateway is used to connect Power BI Service with on-premises data sources. It allows refreshing data from on-premises data sources in the cloud.
Data Transformation and Modeling:
- What is Power Query?
- Power Query is a data connectivity and data preparation technology that enables users to discover, connect, combine, and refine data.
- Explain the difference between calculated columns and measures in Power BI.
- Calculated columns are computed at the row level, whereas measures are computed at the aggregated level.
- How do you handle data inconsistencies or errors in Power BI?
- Power BI provides various data cleansing tools in Power Query like removing duplicates, replacing values, and handling errors.
- What is data modeling in Power BI?
- Data modeling involves creating relationships between tables, defining calculations, and optimizing the data model for better performance.
- How do you create a relationship between tables in Power BI?
- Relationships can be created by dragging and dropping related fields between tables in the Relationship view.
Visualization and Reporting:
- What are slicers in Power BI, and how do they work?
- Slicers are visual filters that allow users to filter data in reports interactively.
- How can you create custom visuals in Power BI?
- Custom visuals can be imported from the marketplace or created using the Power BI SDK.
- Explain the difference between calculated columns and measures in Power BI.
- Calculated columns are computed at the row level, whereas measures are computed at the aggregated level.
- How do you create a custom hierarchy in Power BI?
- Custom hierarchies can be created by dragging fields onto each other in the Fields pane.
- What are bookmarks in Power BI, and how do they work?
- Bookmarks are used to capture the current state of a report page, including filters, slicers, and selections, and can be revisited later.
DAX Functions:
- What is DAX (Data Analysis Expressions)?
- DAX is a collection of functions, operators, and constants used in Power BI for data analysis and calculations.
- Explain the difference between CALCULATE and FILTER functions in DAX.
- CALCULATE is used to manipulate filter context, while FILTER is used to apply a filter to a table or expression.
- How do you use RELATED and RELATEDTABLE functions in DAX?
- RELATED is used to retrieve related values from a lookup table, while RELATEDTABLE returns a table related to the current table.
- What is the difference between SUM and SUMX functions in DAX?
- SUM calculates the sum of values in a column, while SUMX calculates the sum of an expression evaluated for each row in a table.
- How do you use CALCULATETABLE function in DAX?
- CALCULATETABLE function evaluates a table expression in a modified filter context.
Data Visualization Best Practices:
- What are some best practices for designing effective Power BI reports?
- Use consistent formatting, provide context with titles and descriptions, choose appropriate visuals, and prioritize simplicity.
- How do you optimize report performance in Power BI?
- Use DirectQuery mode for large datasets, minimize calculated columns, and optimize DAX calculations.
- What is the importance of storytelling in data visualization?
- Storytelling helps in conveying insights effectively by connecting data with narrative and context.
- How do you choose the right visualization type for your data?
- Consider the nature of the data (categorical, numerical, temporal), the message you want to convey, and the audience's preferences.
- How can you enhance the interactivity of Power BI reports?
- Use slicers, drill-through pages, bookmarks, and tooltips to make reports more interactive and engaging.
Advanced Topics:
- What is the Power BI REST API, and how can it be used?
- The Power BI REST API allows developers to programmatically access and manage Power BI resources like datasets, reports, and dashboards.
- How do you implement row-level security in Power BI?
- Row-level security can be implemented using role-based security to restrict access to specific rows based on user roles and permissions.
- What is Power BI Embedded, and when is it used?
- Power BI Embedded allows developers to integrate Power BI reports and dashboards into custom applications.
- How do you use Power BI with big data sources like Hadoop or Spark?
- Power BI can connect to big data sources using connectors like HDInsight and Spark, enabling analysis and visualization of large datasets.
- What are some common data preparation challenges in Power BI, and how do you overcome them?
- Challenges include data cleaning, handling missing values, and transforming data from different sources. Solutions involve using Power Query for data transformation and modeling.
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