Starting a career in Power BI can be an exciting experience, but navigating the interview process takes preparation and knowledge. In this blog, we’ll look at some of the most common interview questions that newcomers to Power BI face. Provide yourself with the information you need to successfully demonstrate your skills and land that ideal job.
Power BI is a suite of corporate Intelligence tools, techniques, and procedures for extracting meaningful information from raw corporate data by linking, manipulating, and visualizing raw data sets from many sources.
It provides the necessary capabilities for developing interactive dashboards and live reports that can be shared and published across multiple platforms to assist business customers and other interested parties in making better decisions. Planners and decision-makers can track their market progress using competitive and carefully categorised information.
Power BI offers an easy interface for connecting, transforming, and visualising raw business data from many sources. Even non-technical people can extract useful information from their business data and utilise it to make more informed decisions. It offers a secure cloud service that allows customers to view reports and dashboards in real-time and share them with additional company users and stakeholders.
Power Query and Power Q&A are two AI tools available in Power BI. You can create dashboards with Power Query by only typing in the columns and graphics you want to include. While Power Q&A allows you to analyse data by voicing commands.
Small companies may use Power BI Desktop to visualise their business data without having hired a separate data analysis team.
Self-service BI, also known as Self-service Business Intelligence (SSBI), is a data analytics, reporting, and visualisation strategy that allows users to build easy-to-use and actionable dashboards practically instantly.
The most important feature of SSBI is that users are not required to be proficient when it comes to data reporting. They can modify data as needed for their business by using useful filters and data manipulation capabilities, and then create reports. Microsoft SSBI is divided into two parts:
(i). Excel BI Toolkit
(ii). Ms Power BI
Power BI, a cloud-based data reporting and visualisation application, allows users to generate reports online. Once reports have been ready, users can share them with teammates. This feature of Power BI has made it very popular among company employees. As a result, Power BI is both an interesting and potential professional path.
Power BI has many features. Amongst the most interesting are:
Power BI is made up of five distinct components.
Data can be filtered automatically using various filters provided in Power BI. Filters may be divided into three types: page-level filters, drillthrough filters, and report-level filters.
When compared to other BI programs such as Tableau, Power BI gives better features and data manipulation tools. A single user can connect to various data sources without any coding or data analytics knowledge. Power BI, as a Microsoft product, is tightly connected with other Microsoft technologies such as Office 365, SharePoint, and Bing.
The free edition of Power BI Desktop allows users to analyse datasets up to 1GB in size and 10,000 rows of data transmission every hour. Furthermore, it includes capabilities such as Power Query, which allows users to readily visualise datasets by using simple English commands.
The following are the building blocks of Power BI:
Power BI may connect to a variety of data sources, but they are classified as follows:
DAX stands for Data Analysis Expression, a formula language used to create calculated measures, columns, fields, and customised tables. It is a set of values, operators, and functions that together form an expression for calculating values.
Here is a basic sample for DAX expression.
Total Sales = SUM(Sales[SalesAmount])
Power BI Gateway is a tool for accessing data from a private network. When a user accesses data from on-premises, the request passes through a Gateway. Power BI Gateway gives a fast and secure connection over the on-premises network and minimizes the chances of interruption in data access due to network failure.
We can use PowerBI. Row-Level Security allows you to hide confidential data in Power BI. Row-Level Security prohibits data access depending on the roles provided to a profile or group of people.
To summarise, using Row-Level Security allows you to create rules that filter data based on the responsibilities granted to users, allowing you to hide or restrict access to sensitive information within Power BI.
The table can only be filtered and modified using these two functions. These can be used to add to existing filters or queries, override filter context in queries, or remove filter context from queries.
Calculated columns are additional columns that we construct and calculate with DAX expressions.Measures, on the other hand, are calculated using DAX expressions but do not appear in the data tables at all.Calculated columns are reviewed for each row, while measures are only evaluated at the level of dimension at which they are displayed.
In a normal filter, the user cannot connect with the dashboard, whereas a slicer allows users to connect with Reports and Dashboards.
Time Series helps you to analyse data patterns such as trends, cyclicity, and seasonality with time-based graphs and visualisations. It is an excellent approach to represent data that changes over time so that patterns may be clearly seen. It is commonly used for event analysis, forecasting, and prediction.
It is a design method for putting visuals above shapes. In other words, it is a method of execution that can be used when reports include multiple elements.
In Power BI, the term “z-order” refers to the order in which visuals (such as charts, tables, and other report elements) are stacked or layered on top of each other in the report canvas. The “z” in z-order stands for the third dimension in a three-dimensional space, with “x” and “y” representing the horizontal and vertical dimensions, respectively.
Power View is a data visualization technology to create interactive graphs, charts, maps, and many other visuals. It helps in analyzing the data patterns and generating meaningful insights. Power View is available for multiple tools and platforms like Excel, SharePoint, SQL Server, and Power BI.
Power BI Desktop | Power Pivot for Excel |
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In Power BI, KPIs (Key Performance Indicators) are a type of visual that shows a specific statistic or measure that is critical in analysing the performance of a business, project, or process. KPIs assist organisations in tracking progress towards their goals and objectives and making data-driven choices. KPIs are displayed in Power BI as single data points or small charts that provide a quick a snapshot of performance against predefined targets.
SUMMARISE()
SUMMARIZECOLUMNS
Calculated Columns are DAX expressions that are computed during the model’s processing/refresh process for each row of the given column and can be used like any other column in the model.
Calculated columns are not compressed and thus consume more memory and result in reduced query performance. They can also reduce processing/refresh performance if applied on large fact tables and can make a model more difficult to maintain/support given that the calculated column is not present in the source system.
Three fundamental concepts of DAX are as follows:
DAX or Data Analysis Expression is a functional language that can create calculated columns and/or measures for smarter calculations to limit the data the dashboard has to fetch and visualize.
| Power BI Dataset | Report | Dashboard |
| Source data provides the basis for creating reports and visuals. | Power BI Desktop files may contain several pages of reports. | Visuals taken from different reports make up this slideshow. |
| Data are contained within a model or available via direct query connection from its source. | Built for interactive, in-depth analysis of specific datasets. | Built for easy visuals and metrics collection from multiple datasets. |
In Power BI, a measure is a computed field that is used to derive critical insights and data properties for DAX statements. Total and maximum salary, for example, would be examples of metrics in a Table of employee wages for an organisation.
M language is used to filter data in Query editor.
CORR stands for the Correlation function or coefficient. It is used to find the relationship between two given values or attributes. Out of the plentiful correlation functions, Pearson correlation is the most popular. Its output always falls between -1 and 1 by design.
Positive correlation signifies that both values being compared increase simultaneously. In comparison, a negative correlation means that the other will decrease when one of the variables increases.
Steps to apply correlation in Power BI using quick measure:
Load the table in Power BI from your desired data source – SQL Server, CSV, web API calls, etc
Reach for the ‘Quick measure’ option under the ‘home’ tab.
Under the drop-down menu, search for select a calculation and proceed to Mathematical calculations
Under the mathematical calculation, you will find the correlation coefficient.
At last, we need to give three values to initiate the correlation function – Category, Measure X and Measure Y.
You have successfully found the correlation between measure x and measure y. You can display the value onto the dashboard using the card menu from the visualization panel.
x-Velocity is the in-memory data analytics engine in Power Pivot, where all the data is stored in RAM in the form of columnar databases.
There are two types of relationships in Power Bi Desktop
By Manually specifying the primary and foreign keys between tables
By letting Power BI detect the relationships automatically.
Bookmark in Power BI helps you to capture the configured view of a report page in a specific time. This includes filter and state of visual which can use a short cut to come back to the report that you can add as a bookmark.
If you want to calculate numeric values, then use MAX. However, if it is for non numeric values, then you should use MAXA.
You can basically save two types of data in Power BI.
Tables of facts:
In most circumstances, the centre table in a data warehouse’s star structure is a fact table that stores quantitative information for analysis that is not normalised.
Tables of Dimensions:
It is a table in the star framework that allows you to store attributes and dimensions that characterise objects in a fact table.
Power BI online contains an option for publishing on web that will generate a link address for the Power BI report. You can share these links to others, which is called embed code.
On-premises or in the cloud, Power BI provides a scalable and unified platform for data collection, refinement, analysis, and presentation. Through interactive dashboards and data-rich, easy-to-understand reporting, it provides organizations with a 360-degree view of their operations. It is a part of Microsoft Business Intelligence (MSBI) suite, and it includes a variety of services, products, and applications.
In Power BI, a user can export any dashboard or visual. To export your data, choose the ellipses (3 dots) on the top-right side of any visualization and choose the icon: Export data. Your data is exported as an a.CSV file. You can even save and open the file in Excel.
A Parameter in Power BI is a dynamic filter that is used in the calculation fields. It is based on the parameter value result that can vary.
We can use both Distinct() and Values() functions to return the values into a column or cell on the worksheet. The difference between them is that the Values() function returns blank values along with unique values, whereas the Distinct() function returns only unique values.