Complete Power BI Interview Questions and Answers
1. What is Business Intelligence?
Business Intelligence (BI) is a technology-driven process that analyzes data to provide actionable information, assisting corporate executives, business managers, and other users in making informed business decisions.
2. What is Self-Service BI?
Self-service BI allows business users to access and explore data without requiring a background in BI, data mining, or statistical analysis, making data analysis more accessible.
3. What is Power BI? Why is Power BI so powerful?
Power BI is a suite of business analytics tools for analyzing data and sharing insights. It connects to multiple data sources, transforms data into engaging visualizations, and is known for its user-friendly interface, robust data modelling, and the ability to create interactive dashboards that can be accessed across devices.
4. What are the components of Power BI?
- Power Query: For data discovery, access, and transformation.
- Power Pivot: For data modelling.
- Power View: Used for creating charts and tables.
- Power Map: Helps in creating geospatial data representations.
- Power Q&A: Enables natural language processing for data queries.
5. What are reports in Power BI?
Reports in Power BI provide a multi-perspective view of data using visuals to represent various findings. Reports can range from a single visual to pages full of visualizations.
6. What are dashboards in Power BI?
A dashboard in Power BI is a single-page canvas that displays visualizations to tell a story. Due to its single-page limitation, only key visuals should be included.
7. What is a DAX function?
DAX (Data Analysis Expressions) is a functional language used in Power BI to create custom calculations in calculated columns, measures, and calculated tables.
8. What is M language?
M is a case-sensitive programming language used in Power Query for data transformation and manipulation.
9. What are two types of connectivity?
- Import Mode: Data is imported and stored in the PBIX file, allowing offline data analysis.
- Direct Query Mode: Data remains in the source, ensuring real-time data access.
10. Explain the various data sources that can be used in Power BI.
Power BI supports various data sources, including:
- Files (Excel, CSV, XML, JSON)
- Databases (SQL Server, Oracle, MySQL)
- Cloud services (Azure, SharePoint, Google Analytics)
11. What are the various components in the architecture of Power BI?
- Power BI Desktop: Used for developing reports.
- Power BI Service: A cloud-based service for sharing and collaborating on reports.
- Power BI Mobile: This is for viewing reports on mobile devices.
- Power BI Gateway: Connects on-premises data sources to Power BI.
- Power BI Embedded: Embeds Power BI reports in custom applications.
- Power BI Report Server: Hosts reports on-premises.
12. What are the building blocks of Power BI?
- Visualizations: Graphical representation of data.
- Datasets: The data source for Power BI visualizations.
- Reports: A collection of visualizations.
- Dashboards: A single-page display of visualizations.
- Tiles: Individual visualizations in reports or dashboards.
13. Explain the .pbix file format.
A .pbix file is a Power BI Desktop file containing data queries, data models, visualizations, and settings. It can be renamed to .zip to explore its contents.
14. What are the various views in Power BI Desktop?
- Report View: For creating reports.
- Data View: This is for data shaping and analysis.
- Relationship View: For managing data relationships.
15. What are the various features of Power BI Query Editor?
- Connecting to data
- Shaping and combining data
- Grouping rows and pivoting columns
- Creating custom columns
- Using query formulas
16. What is the Lock Aspect in Power BI?
Lock Aspect keeps the proportions of a visual intact when resizing.
17. What are common data shaping techniques?
- Removing columns/rows
- Adding indexes
- Sorting data
- Pivoting and unpivoting data
18. Where is data stored in Power BI?
Data is stored in fact and dimension tables within the data model.
19. What is the business need for Power BI?
Power BI aids in data visualization and reporting, which helps organizations make data-driven decisions, monitor performance, and set business goals effectively.
20. How can we calculate average in Power BI?
- By changing a measure’s aggregation to Average.
- Using DAX:
AVERAGE([ColumnName]).
21. What is Power BI Cloud?
A cloud-based platform where users can create, view, edit, and share Power BI dashboards and reports.
22. How can one connect to an Oracle DB in Power BI?
By selecting Get Data > Database > Oracle Database, inputting server details, and choosing the connection mode (Import/Direct Query).
23. How can we represent different levels of hierarchy in one visualization?
By grouping data fields into a hierarchy and enabling the drill-down option.
24. How can one connect a SQL server in Power BI?
By going to Get Data > SQL Server, entering server details, and authenticating the connection.
25. What is embedded Power BI?
A Microsoft Azure service allowing developers to embed Power BI reports and dashboards into custom applications.
26. What are the different relationships in Power BI?
- One-to-One
- One-to-Many
- Many-to-One
27. Explain the difference between merge and append.
- Append: Combines data by adding rows.
- Merge: Joins data based on matching criteria between tables.
28. What are visualizations in Power BI?
Visuals that represent data, such as charts, tables, and maps.
29. What is Power BI Designer?
A tool under the Power BI suite that enables report and dashboard creation.
30. What is the Power BI Service?
A cloud service for viewing and sharing reports and dashboards.
31. Explain the difference between Power BI Pro and Premium.
- Pro: Individual licenses for full access to create and share content.
- Premium: Licenses for larger-scale content sharing without per-user costs.
32. What is z-order in Power BI?
The arrangement order of elements on a report canvas.
33. Explain custom visuals in Power BI.
Visuals created outside of Power BI Desktop and imported to enhance reports.
34. How can we categorize the types of users in Power BI?
- Analysts
- Business Users
- IT Professionals
- Developers
35. How can each category manager see their category’s sales, while the CEO sees all?
By configuring dynamic row-level security.
36. Why use the selection pane in Power BI?
For better control over visuals and creating bookmarks.
37. Explain the various joins in Power BI.
- Left Join
- Right Join
- Full Outer Join
- Inner Join
- Left Anti Join
- Right Anti Join
38. What is the purpose of the ‘Get Data’ icon in Power BI?
To access and connect to various data sources.
39. Name different filters used in Power BI.
- Visual-level Filters
- Page-level Filters
- Report-level Filters
40. What is grouping in Power BI?
A method for grouping data elements to create logical categories.
41. How are slicers used?
To filter reports interactively.
42. What are KPIs in Power BI?
Key Performance Indicators (KPIs) are metrics used to measure performance against goals.
43. What is Power BI Q&A?
A natural language query tool in Power BI for exploring data.
44. How can we create calculated columns in Power BI?
By selecting New Column and using DAX formulas.
45. What are combination charts in Power BI?
Charts that display multiple data series, such as line and bar charts.
46. Explain security levels in Power BI.
Power BI uses Azure Active Directory for user authentication and data security.
47. Describe different visual segments in Power BI.
- Distribution: Histograms, KDE plots.
- Trend: Line charts.
- Maps: Geographic visuals.
- Relation: Scatter and bubble charts.
- Comparison: Bar and funnel charts.
48. What are the advantages of using variables?
- Reusability
- Interpretability
- Scoping
49. Can SQL be used in Power Query Editor?
Yes, as the source for Power Query/M functions.
50. What does ‘X’ imply in functions like SUMX and AVERAGEX?
It indicates that the function works in a row context.
51. Why prefer calculated measures over calculated columns?
Calculated measures consume less memory and improve performance since they are not stored in the data model.
52. Difference between COUNT and COUNTD?
- COUNT: Counts non-null values.
- COUNTD: Counts distinct non-null values.
53. What do ‘P’ and ‘S’ imply in VAR.P and VAR.S?
- P: Population variance.
- S: Sample variance.
54. What is a Bookmark?
A feature that captures the state of a report page, including filters and visual states.
55. Example of a cross-table visual?
Matrix visual allows multi-dimensional data exploration.
56. How can one create hierarchies in Power BI?
By dragging and dropping related fields to form a hierarchy.
57. Two ways to navigate reports?
- Buttons with actions for page navigation
- Using bookmarks
58. How to scrape data from the web in Power BI?
Select Get Data > Web, input the URL, and import data through Power Query.
59. What is the difference between histograms and bar charts?
- Histograms: Show data distribution.
- Bar Charts: Compare categorical data.
60. How to handle an inactive relationship between tables in Power BI?
Activate relationships as needed using DAX: USERELATIONSHIP().
61. How to create filters in Power BI?
By adding fields to the filter pane or using slicers.
62. How to sort data in Power BI?
Using the Sort by Column option in visuals or data view.
63. Differences between MSBI and Power BI?
MSBI is a suite for data integration and reporting, while Power BI focuses on data visualization and analysis.
64. How to publish a dashboard in Power BI?
Use the Publish button in Power BI Desktop to upload to a workspace.
65. How can Power BI dashboards be shared?
Through the Share option, content packs, or by exporting to PDF/PPT.
66. What is MDX in Power BI?
A query language for tabular models and Power BI datasets.
67. How to add page-level filters in Power BI?
Drag fields into the Page Level Filters section.
68. How to combine two columns in Power BI?
Using DAX: NewColumn = [Column1] & [Column2].
69. How to change date format in Power BI Query Editor?
Select the date column, go to Modelling tab, and choose the format.
70. How to edit interactions in Power BI?
Use the Edit Interactions feature in the Format tab.
71. Difference between LTRIM and RTRIM?
- LTRIM: Removes spaces from the left.
- RTRIM: Removes spaces from the right.
72. DAX for dynamic security?USERNAME() and USERPRINCIPALNAME().
73. What is a workspace in Power BI?
An environment for sharing content like reports and dashboards.
74. How to show percentages in Power BI?
Create a calculated measure using DAX.
75. How to filter Top N in Power BI?
Use the Top N option in the Filter Pane.
76. Why can’t Top N be used for report/page-level filters?
It is designed for specific visuals.
77. What is query collapsing?
Converting Power Query steps into SQL for optimized data processing.
78. Difference between MAX and MAXA?
- MAX: For numeric values.
- MAXA: For both numeric and non-numeric values.
79. What is the CORR function?
It returns the correlation between two variables.
80. What are content packs in Power BI?
Packages of reports, dashboards, and datasets for sharing with others.
81. How to use Power BI in MS Excel?
Through the Analyze in Excel option for reports in Power BI Service.
82. How to change X-axis value in Power BI?
By creating a dynamic column using DAX.
83. Available cross-filter directions in Power BI?
- Single: Filters one way.
- Both: Filters both ways.
84. What is bidirectional cross-filtering?
Allows filters to flow in both directions across table relationships.
85. What is OData feed in Power BI?
A protocol for accessing data from URLs with simplified request handling.
86. What is forecasting in Power BI?
A feature that predicts future trends based on current data.
87. What is Power BI Data Gateway?
A tool that connects cloud services to on-premises data sources.
88. How to refresh a Power BI report on cloud?
Use Data Gateway for reports hosted on Power BI Service or SharePoint.
89. Data refresh options in Power BI?
- Package Refresh
- Tile Refresh
- Visual Container Refresh
90. What is Power Map?
An Excel add-in for creating 3D visualizations with geo-coded data.
91. Differences between live/direct query connections and local data models?
Local models allow full control over data manipulation, while live connections restrict some functionalities.
92. What is incremental refresh?
A feature that refreshes only new data, reducing processing time.
93. How to use the first row as column titles?
Select Use First Row as Headers in Power Query.
94. What is a single-page visualization canvas called?
A Power BI dashboard.
95. Example of a DAX for a ‘bad hire’ column.IF(OR((([HireDate]-[TermDate])) >= 61, ISBLANK([TermDate])), 0, 1)
96. DAX formula for the previous month.Previous Month = IF(Sales[Today Month] = 1, 12, Sales[Today Month] - 1)
97. How to display thousands separator in Power BI?
Select the column and check the Thousands Separator in the Modelling tab.
98. What are data alarms?
Alerts that notify when data exceeds set thresholds.
99. Visualization for showing relationships between three values?
Bubble Chart with a logarithmic scale.
100. What happens in ‘In-focus’ mode?
The selected tile expands to full screen.
101. How to add terms into Q&A?
Use Modelling and Synonyms in Power BI Desktop.
102. Function for extracting the last period’s balance?LASTNONBLANK
103. What are data invigoration steps in Power BI?
- Visual compartment
- Tile refresh
- Bundle invigorate
- Display/data refresh
104. What to keep in mind while sharing visualizations outside the organization?
Ensure data privacy and choose the appropriate sharing method.
105. DAX expression for checking a product code.IF(CONTAINSSTRING([ProductCode], "ex"), "Yes", "No")
106. Chart for comparing data side by side?
Bar Chart
107. Chart for showing correlation between two variables?
Scatter Plot
108. What is Row-level security in Power BI?
A feature that restricts data access for certain users based on their role.
109. What is natural language search in Power BI?
Power BI Q&A allows users to ask questions using natural language.
110. Differences between Power BI and SSRS?
Power BI focuses on data visualization and interactive reports, while SSRS is geared towards paginated, operational reports.
111. Drawbacks of using Power BI?
- Limited handling of large datasets.
- Dependency on internet connectivity for cloud services.
- Limited customization of visuals without code.
112. Differences between Power BI and Tableau?
Power BI is more budget-friendly and integrates seamlessly with Microsoft products, while Tableau is preferred for complex data visualizations and deeper analytics.