Power BI Interview Questions

Whether you are a business intelligence analyst, developer, or administrator, you will find it worthwhile to acquire business intelligence and visualization skills. Among the most widely used data reporting and visualization tools is Power BI developed by Microsoft in 2013. Power  BI is a collection of business analytics tools that have grown to become indispensable in analyzing data and drawing insights by creating, viewing, and publishing reports using interactive dashboards. 

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If you intend to develop these important skills, the Microsoft Power BI certification training course should be your first consideration. This course will help you familiarize yourself with creating dashboards and reports from various sources of data to provide your business with valuable insights that are important for decision-making. 

Power BI Interview Questions

Professionals who are pursuing business analyst, web developer or various administrator roles are bound to encounter Power BI questions during their interviews. Therefore, taking some time to build knowledge and application around Power Bi will certainly help make a good impression in the interview. 

Here are common Power BI questions that one should expect in an interview.  

1. Define self-service Business Intelligence

Abbreviated as SSBI, self-service business intelligence is a data analytics methodology that promotes a culture of interacting with, understanding, and drawing insights from data generated in the business without necessarily having a technical background in IT, statistical analysis, or business intelligence. Thus, SSBI makes it possible for anybody with a basic understanding of data to create reports and interactive dashboards to draw insights.    

2. What are the three core Power BI tools?  

To make it flexible to use, Power BI consists of three core tools which are:

• Power BI desktop is best suited for desktop computers specifically Windows 10 operating systems and higher. 
• Power BI Service usable online as a SaaS tool for the cloud platform. 
• Power BI mobile applications for Windows, iOS, and Android devices. 

3. Which data sources can Power BI connect to? 

Power BI can connect to a wide range of data sources under the following categories. 

• Files: Including Excel (.xlsx, xlxm), Power BI desktop files (.pbix) and comma separated value (.csv)
• Content Packs: A content pack is basically a Power BI package containing content like documents or files that have been stored together. There are two types of content packs, those created by users within the business such as reports, datasets, or dashboards, and those that come from service providers like Google Analytics and Salesforce. 
• Connectors: Power BI Connectors refer to a layer of data connectivity that lets users integrate Power BI with various data sources including files, databases, data warehouses, business applications, OLAP systems, social networks, big data, cloud storage.               

4. How is data stored in Power BI? 

After data is loaded in Power BI, it is stored in the form of tables in two ways which are:

• Fact tables: Fact tables store quantitative data and are not normalized. Fact tables store measurements, metrics, or facts of a business process.
• Dimension tables: Dimension tables store the qualitative information of a business process i.e the attributes and dimensions of the data in the fact tables. 

5. Name the different types of filters used in Power BI Reports

There are four different levels at which filters can be applied to data in Power BI. These are:

• Visual-level filters: Visual-level filters are applied to individual visualizations and can be done on data as well as on the calculations used within the visualizations. 
• Page-level filters:  Page-level filters are applied on a particular page within a report. Thus it is possible to have each page in a report with different page-level filter conditions applied to it.  
• Report-level filters: Reports are usually made of multiple pages. Report-level filters are applied to the entire report including visualizations and pages in the report. 
• Drillthrough filters: In this type of filter lets users create a page in their report that focuses on specific entities. 

6. What are paginated reports in Power BI? 

A paginated report is a document-style page report, also known as pixel-perfect, that has been formatted to fit on a page for printing or sharing purposes. These reports are designed to display all the data on a table even if the data is spread across multiple pages and can be expanded either vertically or horizontally to enlarge data for a better view. The extension used for paginated files is.RDL.

7. What is DAX in Power BI?  

Referring to Data Analysis Expression, DAX is a formula expression language used with visualization tools to perform data calculations and analysis on Power BI columns and fields. DAX does not modify or insert data in columns. Expressions include functions, operators, and constants. The Power BI Desktop hosts a library containing over 200 DAX functions that can be used to perform complex calculations on data.  

8. List the data types in DAX. 

The data types available in DAX are 

• Integer
• Binary 
• Currency
• Boolean 
• DateTime 
• String 
• Variant 
• Decimal

9. What is Power Query and which language is used in the Power Query? 

Power Query is a Microsoft Excel feature that is available on Power BI. It is a self-service ETL tool that is used to import data from various sources and then clean, transform, shape, and load the data for analysis. Power Query features a simple-to-use user interface and allows users to set up a query once and reuse it by refreshing it. 

Power Query editor uses the M-code programming language. 

10. What is query folding in Power Query? 

Query folding is a feature in Power Query designed to enhance performance and scaling in Power Query. It is the process by which code in the Power Query Editor is translated into SQL statements so that queries are executed at the source of data and not in the client machine. Thus the data cleansing and transformation processes take advantage of the source database resources.  The advantage it presents is that where the client machine has fewer resources, it can still perform optimally by importing smaller filtered datasets.  From the SQL database. 

11. What is Power Pivot and what is its use in Power BI? 

Power Pivot is an Excel function available on Power BI that is used to import, manipulate, and analyze datasets created from various data sources for the purpose of decision-making in business. Power Pivot offers highly compressed in-memory data storage, fast aggregation, and calculation. 

12. What is an advanced Editor in Power BI? 

This is an editor found within the Power Query Editor that is used to view the M-code of any query. Its function is to view the syntax of the query that will be run on the editor. 

13. Can Power BI be used in mobile devices? 

Yes. Power BI features a component for mobile device applications that supports Windows 10, iOS, and Android-powered devices. These applications are available on app stores like the Google Playstore, Apple App Store, and the Microsoft Store. Also, the Power BI service and Power BI server are accessible but are not optimized for mobile devices.  

Conclusion 

Power BI is an indispensable data analytics and visualization tool in any organization. It is built with the capabilities required to harness data generated in business to enhance sound decision-making. For professionals who interact with data in the course of their duty and many others, Power BI skills can be a valuable addition to their skills arsenal.