1. What is Power BI?
Power BI is a suite of business analytics tools to analyze data and share insights. To create meaningful reports and dashboards, Power BI provides a variety of: Data connectors, Data transformation tools, Visualization options.
2. How do you connect to data sources in Power BI?
Power BI provides a variety of connectors for connecting to different data sources, including Excel files, SQL Server databases, Azure services, and many others.
To connect to a data source, select the appropriate connector and select the tables or data to import.3. What are the different components of Power BI?
Power BI consists of several components which have specific functions related to data transformation, modeling, and visualization. The Components of Power BI, Power Query, Power Pivot, Power View, Power Map, Power BI Desktop.
4. What is DAX and how is it used in Power BI?
Data Analysis Expressions is a formula language to create custom calculations in Power BI. It is used in measures, calculated columns, and calculated tables. DAX allows to create Complex calculations, Hierarchical structures.
5. What are the best practices for creating effective Power BI reports?
The few best practices for creating effective Power BI reports are: Start with a clear objective and audience, Select the right visuals for the data being presented, Using appropriate color schemes and font sizes, Ensure the report is easy to navigate and interact with.
6. How do you create a report in Power BI?
To create a Power BI report, first import the data to analyze then create visualizations. Use the drag-and-drop interface in Power BI Desktop. After creating visualizations, Add them to a report page and customize the layout, formatting, and interactivity as needed.
7. How do you share a Power BI report with others?
Power BI reports can be shared with others in a variety of ways: Publishing to the Power BI service, Embedding in other applications: Access to the report can be controlled through permissions and security settings in Power BI.
8. How would you use Power Query to transform data from multiple tables into a single fact table?
To transform data from multiple tables into a single fact table, use Power Query to perform the following steps: Import the tables into Power BI and create relationships between them. Use the Power Query Merge Queries option to combine the related tables into a single table. Use the Group By option to aggregate the data. Use the Pivot option to reshape the data into a flat format.
9. What are the steps required to optimize the Power BI report performance?
To optimize the Power BI report performance with large data, use the following techniques: Import data into Power BI using DirectQuery Use the Query Reduction feature in Power Query Use the Import or DirectQuery mode to reduce the number of calculations Use the incremental refresh option to limit the amount of data
10. How would you use Power BI to create a drill-through report?
To create a drill-through report in Power BI, these steps are required, Create a summary report with high-level data.Create a detailed report along with underlying data.Create a button or visual in the summary report to access the detailed report.Set up a filter in the detailed report Use the Drillthrough feature in Power BI.
11. How would you use DAX to create a dynamic calculation that adjusts based on user selections?
To create a dynamic calculation in DAX, Use the following steps: Create a measure to use a SWITCH function to evaluate user selections. Use a slicer or a filter to select the variables used in the SWITCH function. Use a disconnected table to create a list of options to select from. Use a SELECTEDVALUE function to retrieve the user selection
12. How to use Power BI for creating a dynamic visual?
Power BI is used to create a dynamic visual using the below steps: Use a DAX formula to create the measure and calculate the value to be displayed in the visual. Use a slicer or a filter to select the variables used in the DAX formula. Use the Visual Level Filters feature in Power BI to apply the slicer or filter. Use the Sync Slicers feature in Power BI to synchronize the slicer or filter across multiple visuals.
13. State the uses of Power BI?
The important uses of Power BI are: Power BI is used to analyze sales and marketing data. It helps to identify trends and opportunities for growth. To track key performance indicators, power BI allows to create financial reports and dashboards. Power BI assures monitoring operational data in real-time to identify potential issues. Sharing data and insights with team members using interactive reports,dashboards by Power BI.
Power BI can combine data from multiple sources.14. What is self service BI?
Self-service BI refers to a process in which business users are empowered to create their own reports and analysis. This approach is useful to: Access and analyze data in real-time, Better decisions, Gain insights to better business outcomes. Self-service BI tools like Power BI, Tableau, and QlikView provide an intuitive user interface. It helps to connect to data sources, manipulate data, create reports, visualizations, and share with others.
15. Mention the Power BI versions?
The various versions of Power BI are: Power BI Desktop – free, downloadable application for Windows. Power BI Pro – Paid version of Power BI with additional features like data collaboration and sharing capabilities. Power BI Premium – Advanced version of Power BI with additional features such as increased data capacity and higher refresh rates. Power BI Mobile – Mobile app for iOS and Android devices. Power BI Report Server – On-premises solution for creating, publishing and managing Power BI reports.
16. What are the advantages of Power BI?
The Advantages of Power BI are: Data visualization: Power BI allows you to create dynamic and interactive data visualizations. Integration with various data sources: Power BI can connect to a wide range of data sources. Self-service BI: Power BI allows users to create their own reports and analysis. Collaboration: Power BI helps share reports and dashboards with others. Security: Power BI offers robust security features to secure the sensitive data. Cost-effective: Power BI offers a range of pricing options.
17. What is Power pivot?
Power Pivot is a data modeling tool used to Create complex data models Perform powerful data analysis Create relationships between data from different sources Perform data analysis and aggregation Import large data sets from multiple sources.
18. State the key features of Power BI
Key features of Power BI: Data connectivity: Power BI Desktop allows to connect to a wide range of data sources and cloud-based sources. Use the Query Editor to perform Data transformation. Data modeling: Power BI is used to create relationships between tables and create calculated columns and measures. Power BI Desktop offers a range of visualization types, including charts, tables, maps, and custom visualizations. Users can create interactive reports with drill-down functionality and filters to allow for exploration of data. Reports can be shared with others through the Power BI service.
19. What is Power BI Query Editor?
Power BI Query Editor is a powerful tool within Power BI Desktop. It is used to clean, shape, and transform the data. It is a valuable tool to create powerful visualizations and reports for Business analysts, Data analysts, To work with data.
20. Mention the different visualizations available in Power BI?
Power BI offers a wide range of visualizations to represent data in an interactive and meaningful way. Column chart, Bar chart Line chart, Area chart Pie chart, Donut chart Scatter chart, Bubble chart Map chart, Gauge chart
21. State about the language used in Power Query
M is a functional programming language used to define data transformations in Power Query. It allows the creation of custom functions and expressions to manipulate and transform data. M is a powerful language to perform complex data transformations.
22. What is Power BI Designer?
Power BI Designer is a desktop-based application to create and publish Power BI reports. It is a standalone application to be downloaded and installed on a Windows-based machine. It is designed to provide a simplified experience for creating and editing Power BI reports.
23. What are the important features of Power BI?
The important features of Power BI are: Data modeling and transformation Data visualization Data exploration Collaboration Mobile accessibility Integration with other tools
24. Mention some applications of Power BI?
Applications of Power BI are: To track sales performance, marketing campaigns, customer segmentation, and other key metrics. Analyze financial data, including revenue, expenses, profit margins, cash flow, and other financial metrics. Tracking inventory levels, shipping times, delivery performance, and other key metrics in the supply chain. To perform HR Analytics to improve employee engagement, retention, and productivity. Analyze patient data, clinical outcomes, and healthcare costs to improve healthcare quality. Track student performance, enrollment trends, and other key metrics in education.
25. What is Power BI Services?
Power BI Services is a cloud-based business analytics service to easily create and share dashboards and reports. It offers several features to collaborate on reports and visualizations like: Data Sharing Collaboration Data Refresh Security Mobile Access Custom Visualizations
26. What are common visuals available in Power BI?
The common visuals in Power BI are used to represent different types of data patterns effectively.
- Bar and Column charts
- Line charts
- Pie charts
- Area charts
- Scatter plots
- Maps (filled and bubble maps)
- Tree maps
- Waterfall charts
- Funnel charts
27. How do you choose the right visual in Power BI for the data?
To choose the right visual, understanding the audience and the message to be conveyed. It depends on the type of data and the story.
For example:- Bar charts are good for comparing categories.
- Line charts are ideal for showing trends over time.
- Pie charts work for representing proportions.
- Scatter plots are used for identifying relationships between two variables.
28. What are the best practices for creating effective visualizations in Power BI?
The best practices to create effective visualizations are:
- Keep visuals simple and focused.
- Use consistent color schemes.
- Avoid clutter by limiting the number of elements per visual.
- Label axes clearly and provide meaningful titles.
- Use interactivity (filters, slicers) wisely to provide user control over the analysis.
29. What is the difference between a calculated column and a measure in Power BI? How are they used in visualizations?
In visualizations, measures are dynamic calculations used to provide aggregations in the data values. It is used in the various values of visualizations. Calculated columns are column calculated row by row that define categories or groupings. It is stored in the dataset, and is used for filtering and categorizing data.
30. How does the Power BI drill-through feature enhance visualizations?
The drill-through feature enhances visualizations by providing deeper insights. It allows users to right-click on a data point in one visual and navigate to a detailed report page.
31. What is a Power BI slicer, and how does it differ from a filter?
Power BI slicer is a visual tool that is used to filter data in a report by selecting values directly on the visual. It provides a clear view of the available filter options. Filters work behind the scenes, whereas slicers offer an interactive element directly in the report.
32. Explain how to use conditional formatting in Power BI.
Conditional formatting can change the appearance of visuals based on specific conditions. For example,
- To apply different colors to bar charts based on value ranges,
- Highlight the highest and lowest values in a table.
33. What is the role of DAX in Power BI visualizations?
DAX is the formula language used for creating custom calculations in calculated columns and measures. DAX expressions are essential for building complex data models and adding interactivity to visualizations
34. How do you handle a scenario where a Power BI report is slow due to too many visuals?
To improve report performance, follow the below essentials:
- Reduce the number of visuals per page.
- Optimize DAX calculations, especially measures.
- Use aggregations or summarized data where possible.
- Limit the data being processed by applying filters or using DirectQuery for real-time data sources.
- Remove unnecessary interactivity or formatting options that may slow down rendering.
35. How do you handle large datasets in Power BI to ensure optimal report performance?
To optimize Power BI report performance with large datasets,
- Use aggregations to pre-aggregate data, reducing the amount of data loaded.
- Apply incremental refresh to load only new or updated data during refreshes, minimizing processing time.
- Use proper data types and avoid unnecessary columns or rows in your dataset.
- Implement query folding by ensuring as much data processing as possible is pushed to the source database, rather than Power BI handling it.
36. What are the differences between a dashboard and a report in Power BI?
Power BI Report is a multi-page visual representation of the data whereas Dashboard is a single-page (canvas) that contains tiles from one or more reports.
Report is created using Power BI Desktop and can also include various visualizations, filters, and interactions across pages.
Dashboards are created in Power BI Service and offer a high-level view of metrics.
37. Explain the role of DAX in Power BI reports.
DAX is a collection of functions, operators, and constants to create custom calculations and measures.
Example: To calculate a running total using DAX:
38. How would you implement row-level security (RLS) in a Power BI report?
Row-Level Security (RLS) in Power BI is used to restrict data access for certain users based on their role.
To implement RLS:1. In Power BI Desktop, define roles by going to Modeling > Manage Roles.
2. Specify filters for each role based on the data.
3. After publishing the report to Power BI Service, assign the corresponding users to these roles under the “Security” settings of the dataset.
39. State the main components of Power BI Desktop?
The main components of Power BI desktop are:- Power Query: To perform data transformation and cleansing.
- Data Model: defining relationships, creating measures, and calculated columns.
- Report View: To build visual reports and dashboards using visuals like charts and graphs.
40. What is the difference between DirectQuery and Import mode in Power BI Desktop?
In Import Mode, Data is imported into Power BI’s internal storage. The reports use this in-memory data and allows for fast queries. Using DirectQuery, queries are sent directly to the data source each time a user interacts with the report.
41. What are measures and calculated columns in Power BI Desktop?
Measures are dynamic calculations used in reporting. It is based on DAX and is computed during the report run-time. Calculated Columns are static calculations added to the data model. They are calculated when the data is loaded into Power B.
42. What are relationships in Power BI, and how do you define them?
Relationships are used to define how tables interact with each other. They allow users to model complex data. To define relationships: Go to the Model view and Drag and drop the common field between two tables to create a relationship. Choose the cardinality and the cross-filtering direction.
43. How do you handle missing or inconsistent data in Power BI Desktop?
The methods to handle missing or inconsistent data are
Replace values: Replacing null or incorrect values with a default or calculated value.
Remove duplicates: Eliminating duplicate records from the dataset.
Fill down/up: Filling missing values with the nearest available value.
Split columns: For inconsistent data like addresses, you can split a column by a delimiter for better organization.
44. What is the difference between a calculated table and a regular table in Power BI Desktop?
Regular Table is created by importing data from an external data source.
The Calculated Table is created using DAX formulas and is based on existing data in the model. For example, you can create a calculated table that filters a specific range of data:
FilteredSales = FILTER(Sales, Sales[Amount] > 1000)
45. What are some ways to improve Power BI Desktop report performance?
- Use Import Mode instead of DirectQuery for faster queries (where applicable).
- Optimize data models by reducing unnecessary columns and rows.
- Aggregate data at the data source level to reduce the amount of detailed data loaded.
- Limit visuals on a report page to avoid heavy calculations and render times.
- Enable parallel loading in data load options to speed up data refreshes.
46. How do you use bookmarks in Power BI Desktop, and what are their use cases?
Bookmarks in Power BI Desktop allow users to capture the current view of a report, including filters, slicers, and the visible state of visuals. Bookmarks are useful for:
- Creating report navigation to simulate different report pages or states.
- Presenting data stories with different views and insights.
- Interactive reports that combine bookmarks with buttons to allow users to switch between views.
47. State the key features of Power BI Mobile
Touch-optimized Interface that offers pinch-to-zoom and swipe gestures to navigate reports and dashboards.
Mobile Layouts to design Reports specifically for mobile viewing. This allows for optimized visualization arrangement on smaller screens.
Alerts and Notifications when certain thresholds in reports or dashboards are met, providing real-time updates. Offline Access when there’s no internet connectivity.
48. How can you optimize Power BI reports for viewing on Power BI Mobile?
To optimize Power BI reports for mobile devices, several best practices can be followed:
-
Mobile Layout Design: Use the Mobile Layout feature in Power BI Desktop to rearrange visuals for better readability on small screens. You can access this by selecting the “Mobile Layout” option in the “View” tab.
Simplified Visuals: Choose simple and concise visuals that are easy to read on a smaller screen. Avoid cluttered visuals with too much data or too many details.
Prioritize Key Insights: Display the most critical KPIs and visuals at the top of the report. This ensures that users can immediately see the most important information when they open the report.
Responsive Sizing: Use visuals that adapt well to different screen sizes, ensuring that the report looks good whether it’s viewed in portrait or landscape mode.
49. How does the ALL function work in DAX ?
The ALL function is used to remove filters from a specific column or table, allowing you to ignore any existing context for that column or table in your calculation.
Example:50. What is the CALCULATE function in DAX?
CALCULATE: This function is used to change the context of a calculation by applying filters. It can modify the existing context in which a measure is being evaluated, allowing you to compute complex metrics.
Example: