10 Power BI Interview Questions You Must Be Able to Answer
Written by co-founder Kasper Langmann, Microsoft Office Specialist.
There’s an increasing demand for data analysis, visualization, and reporting that led to the opening of thousands of BI-related jobs.
Power BI is one of the most popular and most-used BI tools in the world. That’s why some of the companies have been listing “Power BI familiarity and experience” as one of their requirements in job openings.
If you’re after these jobs, you would need to show your expertise about the tool.
In this article, we’ll be helping you ace your interviews and land your dream job through these 10 Power BI interview questions.
Let’s get started! 👍
*This tutorial is for Power BI Online (also called "Power BI Service").
Table of Content
1. What exactly is Power BI?
If you’ve been using Power BI, then you already have a good idea about what Power BI can do.
However, your interviewer might want to make sure that you know what Power BI is by heart.
To put it simply, Power BI is Microsoft’s business intelligence and analytics solution where you could connect your data, visualize it, and share your findings and insights with your organization.
In some ways, it’s closely related to Microsoft Excel having similar components.
Power BI has 5 main components:
- Power Query
- Power Pivot
- Power View
- Power Map
- Power Q&A
Don’t forget to mention that Power BI isn’t just a single software you download and use. Power BI is like an umbrella of tools with 3 main products:
- Power BI Service (the online version)
- Power BI Desktop (the on-premise version)
- Power BI Mobile
2. Are there any differences between the Power BI Desktop and Power BI Service?
Follow-up question: If so, what are some of these differences?
Power BI Desktop or Power BI Designer is the on-premise (Windows) version of the solution you can download and install on your computer unit. It’s primary use revolves around generating, designing, and publishing Power BI reports.
The desktop version doesn’t need the internet for it to work. The internet is only needed during publishing the reports and sharing them with others.
Some of the features unique to Power BI Desktop include:
- Data transformation, modeling, and shaping
- Calculated columns
- Python and DAX
- RLS creation
Power BI Service, also called Power BI Online and Power BI Portal, is the cloud-based version of the solution. This is primarily for light report editing and collaboration with others. Data modeling is extremely limited.
Some of the features unique to Power BI Service include:
- RSL management
- Gateway connections
Basically, Power BI Desktop is used for modeling and creating Power BI reports while Power BI Service is used for sharing and collaborating with others.
3. What kinds of data sources can you connect to with Power BI?
Though some of the users use Power BI together with Microsoft Excel, there are a lot of data sources you can connect into with Power BI.
These sources can be summarized as follows:
- SQL database
- Flat files
- Azure cloud
- Online apps and services
- Blank Query
- OData feed
- Other sources like Hadoop, Exchange, or Active Directory
With the use of Power BI connectors, Power BI can practically connect with almost any data source.
And if ever the app or service you’re using doesn’t have a connector for Power BI yet, you can ask them for a custom connector. However, you need to change the security settings of the app to allow the usage of custom connectors.
4. What are the key building blocks of Power BI?
When you think about it, the design behind Power BI is to connect data, analyze it, report the findings and insights through visuals to be shared with others.
To achieve these, there are 5 basic blocks in Power BI:
First off, the dataset comes from the data source you connect to Power BI. This is the ultimate source of all the visuals you see in Power BI.
The visuals are graphic representations of your data. They make your data easier to follow, understand, and analyze.
A Power BI report is a page or group of pages where the visualizations reside. You can only have one report per dataset.
The visualizations in a report could then be pinned into Power BI dashboards. The visuals on a dashboard are called “tiles” and are easily customizable.
When creating a dashboard, you can have visuals from different reports. This means the visualizations on a dashboard could also come from different datasets.
5. How do you filter your data with Power BI?
With Power BI, you can filter your data to have an in-depth understanding of them.
There are 4 basic types of filter:
- Drillthrough filter
Visual-level filters filter data and calculations on a single visualization.
Page-level filters are like visual-level filters but on a report page. However, different report pages could have different page-level filters.
Report-level filters are for the entire reports which cover all pages and visualizations.
Drillthrough filters create destination report pages that focus on a specific element or entity.
For a filter to work, you need to have a hierarchy in your data.
6. What is DAX?
Follow-up question: What are some of the most commonly used DAX functions?
DAX (short for Data Analysis Expressions) is a library of functions and operators you can use to query and return data in a table expression.
It allows you to make basic calculations and analyses in Power Pivot and compute calculated columns and fields.
Here’s an example of a DAX function used in creating a date table:
Some of the most commonly used DAX functions include:
- IF, AND, OR, SWITCH
- GEOMEAN, MEDIAN, DATEDIFF
- SUM, MIN, MAX, AVG, COUNTROWS, DISTINCTCOUNT
- VALUES, ALL, FILTER, CALCULATE
7. What can you tell me about Power BI Query?
Power Query is one of the main components of Power BI. It’s an ETL (Extract, Transform, Load) tool you can use to mold, clean, and transform data with buttons instead of formulas.
In Power BI Desktop, there’s a Power Query Editor which is a separate app accessible within the desktop version of Power BI with a single click.
Common usage of the Power Query Editor include:
- Adding and removing columns
- Filtering rows
- Changing data types
That’s not to say you can’t use formulas. There’s an advanced editor where users can use a new programming language called M-Code.
8. What do you know about the Power BI Q&A?
In simple terms, Power Q&A is a Power BI component that lets you ask about your data in natural language and get results.
There’s nothing you have to do to make your data Power Q&A-friendly. Power BI automatically does that.
Here’s the Power Q&A component in action:
To use this component, all you have to do is type in your question on the Power Q&A dialog box and Power BI will interpret your question and show you the results.
9. What is Power View?
All those interactive visuals — charts, graphs, maps, and others — are brought about by Power View.
Not all is Power View available in Power BI, it’s also in Microsoft Excel, SharePoint, and SQL Server.
This is also what makes filtering data possible. It uses the metadata — hierarchies — of the data model to understand how each table, field, and element is connected to one another.
10. What is Power Pivot?
Power Pivot, also known as the DAX Engine, is also one of the main components of Power BI.
It’s a data modeling technology that lets you build data models, create relationships, write calculated columns and measure formulas.
If you’re familiar with Excel, then you must’ve heard of Pivot Tables. That’s because Power Pivot first appeared in 2008 as a downloadable free add-on for Excel.
However, there are a few differences between the data modeling in Power BI Desktop and Excel’s Power Pivot:
- In Power BBI, data modeling supports bi-directional cross-filtering relationships, security, calculated tables, and direct query options.
- In Excel, data modeling only has a single direction (one-to-many) relationships, calculated columns (not tables), and supports import mode only. You also can’t define security roles with Excel’s Power Pivot.
Bonus: How do you use maps in Power BI?
Power Map is another main component of Power BI which enables you to use map visualizations.
There are 4 types of built-in maps in Power BI:
- Map (Basic)
- Filled Map
- ArcGIS Maps
- Shape Map
All of these are available in both Power BI Desktop and Service except for the shape map. As of now, the shape map is still in preview mode.
In Power BI Desktop, you could change the settings about preview features and try them.
Wrapping things up…
With all these interview questions + bonus and all the preparations you’re making, it’s almost a guarantee that you would get that sweet spot.
But to really master Power BI and not just its principles, you need to practice. Some interviewers like practical questions so always anticipate them and prepare in advance. 😊