Microsoft Power BI is a very popular data visualization tool. In this article, we discuss the most frequently asked questions and answers about Power BI interviews.
What is Power BI?
Power BI is a self-service business intelligence tool from Microsoft. It's a collection of software services, apps, and connectors that work together to transform and visualize companies' raw data.
What versions of Power BI are there?
Power BI is currently available in three versions:
Microsoft Power BI Free/Desktop - Users can connect to the data and create the reports with a free license, but it is limited to their use and cannot be shared or published in the workspace.
Microsoft Power BI Pro - This version offers a per-user license; Power BI Pro users can create and share content with other Power BI Pro users.
Microsoft Power BI Premium - This version offers a license for a single user in an organization. Only users with a Pro or PPU license can create and store content in Premium capacities.
How many building blocks are there in Power BI?
This is one of the most common Power BI interview questions. Power BI consists of five building blocks: datasets, visualizations, reports, dashboards, and tiles.
records: Records contain a data source used in reporting.
visualizations: Visuals are pictorial representations of the source data. The visuals are available in reports, dashboards, and Q&A.
reports: A report presents multiple visual representations of a dataset.
Dashboards: A dashboard is one page, and it is limited to one page, it can contain multiple visual elements to present the data in different ways that present important data stories.
tiles: A tile is a snapshot of your data that is pasted onto the dashboard. A tile can be created from a report, dataset, dashboard, Q&A box, etc.
What are the different types of refresh options available in Power BI for published reports?
This is another key Power BI interview question. There are four main types of updates in Power BI: package update, model or data update, tile update, and visual container update.
This applies to Power BI Desktop or files between the Power BI service and OneDrive or SharePoint Online. However, this does not pull any data from the original data source.
It occurs within the Power BI service with data from the original data source. This is done either through the scheduled update or through the update now. A gateway for on-premises data sources is also required.
It updates the cache for tile visuals on the dashboard as soon as data changes, and it does so every 15 minutes. Alternatively, you can update tile data manually by selecting the ellipsis (...) in the upper-right corner of a dashboard.
Visual container update
Once the data is updated, the cached report is updated.
Was ist PowerQuery?
This is an additional part of the core questions for Power BI interviews. It is a powerful data transformation and data preparation engine. It has a graphical user interface for fetching data from various sources (files, webpages, cloud storage, APIs, databases, etc.). You can run this as a free tool in Power BI
What is a Power BI-Gateway?
The gateway acts as a bridge between on-premises data sources and Azure cloud services. The advantages of the gateway are that on-premises data can be used securely in cloud services.
What is DAX?
DAX is one of the important areas of Power BI interview questions, it stands for Data Analysis Expressions used in Analysis Services, Power BI and Power Pivot in Excel, it is a formula language used to do custom calculations on calculated columns and define metrics.
What is a metric in Power BI?
Measures is a calculated field in Power BI DAX. For example total sales, total salaries, average quantity and so on. The output value of the actions is not stored in memory and can have different values in different scenarios and contexts.
What is the difference between SUM and SUMX?
As part of the Power BI interview questions, you may be asked some DAX samples. The SUM looks at a single column as a whole and returns results and does not perform row-by-row evaluations.
Syntax of the SUM function
Example: Total Stores = SUM(Stores_Table[Store_Unit])
The SUM function adds each value from the Store_Unit column of the Stores_Table to return the total number of stores.
SUMX works as row-by-row calculations and iterates through each row to perform the calculations from a specified table. Unlike the SUM function where we can specify a column to run aggregates, SUMX accepts expressions to run the aggregations.
SUMX function syntax
SUMX (<table>, <expression>)
Example: Stores_Table[Sales Amount] = SUMX ( Stores_Table, Stores_Table[Store_Unit] * Stores_Table[Sales_Amount] )
What are the calculated columns in Power BI?
This is part of the Power BI interview questions for DAX. A calculated column is a custom column created by a query or DAX formula from other columns in a table. Because the calculated columns are at the same levels as the tables, they are only calculated when you define them for the first time and after a data refresh. An example of the calculated column is extracting the profit for a product by subtracting the product's purchase price from its selling price.
Profit per product = products [sales price] - products [purchase price]
What are the three Power BI Desktop view tabs?
There are three Power BI Desktop views available:
- report view– This is the default view, it shows all reports containing visualizations, graphs and charts.
- data view- This view allows managing and modifying the imported data in Power BI.
- model view– This view enables the management of data models and relationships.
Some common DAX functions
Here are some common DAX functions that are commonly used.
Aggregation Functions:SUMME, MIN, MAX, AVG, COUNTROWS
Logical functions:IF, AND, OR, SWITCH
Information functions:IS BLANK, IS FILTERED, IS CROSS FILTERED
Filter functions:VALUES, ALL, FILTER, CALCULATE, TOPN
Date and time functions:DATEDIFF, DATEVALUE
Statistical Functions:GEOMEAN, MEDIAN
Other features:UNION, INTERSECT, EXCEPT, NATURALINNERJOIN, NATURALLEFTEROUTERJOIN, SUMMARIZECOLUMNS, ISELEER, VAR
What are slicers in Power BI?
Slicers can be used to refine the data on the canvas. Users select one or more values from a list, which splits the data accordingly. The slicer visualization must first be added to the canvas from the visualization area. Refreshing the dashboard refreshes the data behind the slicers, which can also affect large datasets.
What are filters in Power BI?
The Power BI developer uses filters to refine the data according to the needs. There are three types of filters available, these filters are available on the right side of the canvas; These filters are visual-level filters, page-level filters, and filters that apply to all pages.
Visual level filters:Apply to a single visual on the canvas. First you need to select the visual to configure the filter.
Page level filters:Apply to all visuals on the current page.
Filters that apply to all pages:Apply to all visuals, across all sheets in the current file.
What are bookmarks in Power BI?
We can capture the currently configured visuals of a report page containing filters, slicers, etc. and they will be bookmarked. If you later select a bookmark, you will be taken to the saved report view.
What is Power BI file storage extension?
The Power BI file format is .pbix.
What are custom visuals in Power BI?
Power BI developers can create custom visual code and deploy it in .pbiviz file format. Report developers can then use these files in their Power BI reports.
Below we will discuss some more Power BI interview questions:
What is the difference between import mode and direct query mode?
In import mode, the data is stored in the Power BI desktop cache. Import mode is faster compared to direct query mode because the data is stored in Power Bi-cache.
With a direct query, mode data resides in the database and Power BI connects directly to the database.
What are content packs in Power BI?
A content pack is a package of Power Bi content, including a dashboard, report, and dataset. A content pack is a way to easily share your Power BI content with others. There are two types of content packs: organizational and service content packs. Service content packs are created by providers such as Google Analytics, MailChimp, etc. You must have a Power BI Premium or Power BI Pro license to create an organizational content pack that can be shared with your entire organization or a specific group of people.
What is a paginated report in Power BI?
The paginated report is designed to be best suited for printing. It is created using the Power BI reporting tool (this is a different tool than Power BI Desktop, you need to download it separately). If you have a report that spans multiple pages, paginated reports are your best bet. You can design the headers and footers of the pages according to your requirements.
In this article, we've learned about some of the most popular Power BI interview questions. I hope you find them useful.
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Arindam is an experienced and highly motivated IT enthusiast who enjoys applying his technical expertise to solve critical business needs. A self-directed learner who loves to learn every day. He loves to indulge in cultural diversity and travel to newer destinations.
Arindam has extensive experience in Azure solution implementation and support activities for large enterprise customers, having worked on several development and improvement projects. He is
currently lives in India and works as a Technical Manager for a leading multinational company.
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* Has 10.7+ years of IT experience on Microsoft platforms.
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