200+ Power BI Developer Interview Questions and Answers

Incremental refresh in Power BI allows for loading only new or modified data to improve performance.

• Set up incremental refresh policy in Power BI Service

• Define a range of values for the refresh policy

• Use parameters to filter data based on the refresh policy

• Schedule regular refreshes to update the dataset

ROS stands for Return on Sales in Power BI.

• ROS is a financial metric used to measure the profitability of a company.

• It is calculated by dividing the net income by the total revenue.

• ROS is expressed as a percentage and is used to evaluate a company's efficiency in generating profits.

• For example, if a company has a net income of $100,000 and total revenue of $1,000,000, the ROS would be 10%.

Power BI components include Power Query, Power Pivot, Power View, Power Map, and Power Q&A.

• Power Query: Used for data extraction and transformation.

• Power Pivot: Used for data modeling and analysis.

• Power View: Used for interactive data visualization.

• Power Map: Used for geographical data visualization.

• Power Q&A: Allows users to ask questions in natural language and get answers from data.

The extension of Tableau files is .twb for Tableau Workbook files and .twbx for Tableau Packaged Workbook files.

• .twb files are Tableau Workbook files which contain references to data sources and visualizations

• .twbx files are Tableau Packaged Workbook files which include the data sources and visualizations within the file itself

• Both file types can be opened and edited in Tableau Desktop

Use data modeling techniques, optimize data sources, and leverage Power BI features like aggregations and incremental refresh.

• Utilize data modeling techniques like creating relationships, hierarchies, and calculated columns to optimize data.

• Optimize data sources by using query folding, reducing unnecessary columns, and filtering data before loading into Power BI.

• Leverage Power BI features like aggregations to pre-calculate summarized data for faster query performance.

• Implemen...read more

I have extensive experience with SQL and ADF

• Proficient in writing complex SQL queries for data extraction, transformation, and loading

• Experience in designing and implementing data pipelines using Azure Data Factory (ADF)

• Familiar with scheduling and monitoring data pipelines in ADF

• Worked on integrating SQL databases with ADF for seamless data flow

Types of context refer to the different ways in which data can be analyzed and interpreted in Power BI.

• Row context: evaluates calculations row by row

• Filter context: applies filters to data before calculations

• Query context: used in DAX queries to retrieve data

• Relationship context: determines how tables are related

Power Query is used for data transformation and Power View is used for data visualization in Power BI.

• Power Query is used to extract, transform, and load data from different sources.

• Power View is used to create interactive visualizations and reports based on the transformed data.

• Power Query is more focused on data preparation and cleaning, while Power View is focused on data visualization.

• Power Query can be used to merge, append, and transform data before visualizing it in Po...read more

Use SQL query with ORDER BY and LIMIT to find the 4th highest salary

• Use ORDER BY clause to sort salaries in descending order

• Use LIMIT 3,1 to skip the first 3 highest salaries and get the 4th highest salary

A gateway in Power BI is a bridge that connects on-premises data sources to the cloud service.

• There are two types of gateways in Power BI: On-premises data gateway and Personal gateway.

• On-premises data gateway is used to connect cloud services to on-premises data sources.

• Personal gateway is used for individual users to refresh data within Power BI.

• Gateways ensure secure data transfer between on-premises and cloud environments.

Power BI is a business analytics tool that provides interactive visualizations and business intelligence capabilities.

• Power BI is a Microsoft product used for data analysis and visualization.

• It allows users to connect to various data sources and create interactive reports and dashboards.

• Power BI provides a wide range of visualizations, such as charts, maps, and tables, to represent data.

• Users can create custom calculations, measures, and hierarchies to analyze data in differe...read more

Drill down and drill through are interactive features in Power BI that allow users to explore data in more detail.

• Drill down allows users to navigate from a higher level of data to a more detailed level by clicking on a visual element, such as a bar chart or table.

• Drill through allows users to access a more detailed report or page by clicking on a specific data point within a visual element.

• Both features provide users with the ability to analyze data in a more granular way an...read more

I prefer not to disclose my current CTC.

• I believe that my current salary is not relevant to my qualifications and experience for this position.

• I am more interested in discussing the salary range for this role and how my skills and experience align with the requirements.

• I am open to negotiation based on the overall compensation package offered.

Normalization is a database design technique that organizes data in a structured manner to eliminate redundancy and improve data integrity.

• Normalization helps in reducing data redundancy by breaking down a large table into smaller, more manageable tables.

• There are different normal forms, such as 1NF, 2NF, 3NF, BCNF, and 4NF, each with specific rules and dependencies.

• Normalization ensures data integrity by minimizing data anomalies, such as update, insert, and delete anomalies...read more

A pipeline in data engineering is a sequence of data processing steps that transform raw data into a usable format.

• A pipeline is a set of interconnected data processing components.

• It involves extracting, transforming, and loading (ETL) data.

• Pipelines can be used for data integration, data migration, or data transformation tasks.

• They ensure data quality, consistency, and reliability.

• Examples of data engineering pipelines include extracting data from multiple sources, cleaning ...read more

There are multiple types of filters in Power BI including visual, page, report, and drill-through filters.

• Visual filters apply to a specific visual or group of visuals.

• Page filters apply to all visuals on a specific page.

• Report filters apply to all visuals on all pages of a report.

• Drill-through filters allow users to navigate to a different report page based on a selected data point.

Many to many relationships can be handled using bridge tables or DAX functions in Power BI.

• Create a bridge table to connect the two tables with a many to many relationship

• Use DAX functions like CROSSFILTER or USERELATIONSHIP to handle many to many relationships

• Consider using bidirectional filtering to handle many to many relationships

Coalesce function returns the first non-null value from a list of values.

• Coalesce function is used in SQL and other programming languages.

• It takes two or more arguments and returns the first non-null value.

• If all arguments are null, it returns null.

• Example: COALESCE(NULL, 'hello', NULL, 'world') returns 'hello'.

Write a DAX query in data modeling

• Use CALCULATE function to apply filters and context to calculations

• Use SUMX function to iterate over a table and perform calculations

• Use RELATED function to retrieve related values from other tables

Power Pivot is a data modeling tool in Excel and Power BI that allows users to create complex data models and perform advanced analysis.

• Power Pivot is an add-in for Excel and Power BI

• It allows users to create data models with multiple tables and relationships

• Users can perform advanced calculations and analysis using DAX formulas

• Power Pivot can handle large amounts of data and improve performance

• It is a powerful tool for business intelligence and data analysis

Numerical range parameter is a parameter that defines a range of numerical values for a specific variable or function.

• It is used to specify a range of numerical values that a parameter can take.

• It helps in filtering data based on a specific numerical range.

• For example, a numerical range parameter can be used to filter sales data for products with prices between $50 and $100.

Power BI Premium offers dedicated capacity and advanced features, while Power BI Pro is a subscription-based service for individual users.

• Power BI Premium provides dedicated capacity for larger organizations and advanced features like AI capabilities and paginated reports.

• Power BI Pro is a subscription-based service for individual users and small to medium-sized businesses.

• Power BI Premium allows for larger data volumes and faster refresh rates compared to Power BI Pro.

• Power ...read more

Calculated columns are static values calculated at row level, while measures are dynamic aggregations calculated at query time.

• Calculated columns are stored in the data model and can be used in visuals directly.

• Measures are not stored in the data model and are calculated on the fly based on the context of the visualization.

• Calculated columns are useful for creating new columns based on existing data, while measures are used for aggregations like sum, average, etc.

Relationship cardinality defines the number of instances of one entity that can be associated with the number of instances of another entity.

• One-to-One: Each record in the first entity is associated with only one record in the second entity.

• One-to-Many: Each record in the first entity can be associated with multiple records in the second entity.

• Many-to-Many: Multiple records in the first entity can be associated with multiple records in the second entity.

Show all filter is a feature in Power BI that allows users to display all values in a filter, including those that are not currently selected.

• Show all filter is used to display all values in a filter, even if they are not selected.

• It can be helpful when users want to see all available options in a filter.

• Users can choose to show all values or only selected values in a filter.

Power BI software is used for data visualization and analysis.

• Allows for easy creation of interactive reports and dashboards

• Provides real-time data insights

• Integrates with various data sources

• Enables collaboration and sharing of reports

• Helps in making data-driven decisions

INNER JOIN is used to combine rows from two or more tables based on a related column between them.

• Use INNER JOIN to retrieve rows from both tables that have matching values in the specified column

• Syntax: SELECT column_name(s) FROM table1 INNER JOIN table2 ON table1.column_name = table2.column_name

• Example: SELECT Orders.OrderID, Customers.CustomerName FROM Orders INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID

Duplicates are identical copies of data, while references are pointers to the same data in memory.

• Duplicates are exact copies of the original data.

• References point to the same data in memory.

• Duplicates can lead to inconsistencies in data analysis.

• References are more memory efficient than duplicates.

Clustered Gateway is a feature in Power BI that allows multiple gateway instances to be clustered together for high availability and load balancing.

• Clustered Gateway allows multiple gateway instances to be grouped together to provide high availability and load balancing.

• It helps in distributing the data refresh and query processing workload across multiple gateway instances.

• Clustered Gateway ensures that if one gateway instance fails, another instance can take over to ensure ...read more

There are three connectivity modes in Power BI: Import, DirectQuery, and Live Connection.

• Import mode: Data is imported into Power BI and stored in a dataset.

• DirectQuery mode: Data stays in the data source and queries are sent directly to the source.

• Live Connection mode: Power BI connects directly to the data source for real-time data access.

Gateway connection in Power BI allows on-premises data sources to be accessed securely.

• Install and configure an on-premises data gateway on the server where the data source is located.

• Create a data source in Power BI and select 'On-premises data gateway' as the connection mode.

• Specify the gateway and credentials to establish a secure connection.

• Ensure the gateway is running and connected to the Power BI service for data refresh and access.

Append in Power Query is used to combine multiple tables or queries into a single table or query.

• Append is used to stack tables on top of each other, adding rows from one table to the end of another.

• It is useful when you have multiple tables with the same structure and want to combine them into one.

• You can append tables from different data sources or within the same data source.

• For example, you can append sales data from different regions into a single table for analysis.

Merge in Power Query combines multiple tables into one by matching rows based on specified columns.

• Merge is used to combine tables in Power Query

• You can merge based on one or more columns

• Different types of merges include inner, left outer, right outer, and full outer joins

Sum calculates the total of a column, while SumX calculates the total of an expression evaluated for each row.

• Sum is used to calculate the total of a column in a table.

• SumX is used to calculate the total of an expression evaluated for each row in a table.

• SumX is often used in DAX formulas to perform calculations on a row-by-row basis.

• For example, Sum([SalesAmount]) would calculate the total sales amount, while SumX(Sales, [SalesAmount]*[Quantity]) would calculate the total sa...read more

SQL commands are used to interact with databases and perform various operations like querying, updating, and deleting data.

• SELECT: Retrieves data from a database

• INSERT: Adds new records to a table

• UPDATE: Modifies existing records in a table

• DELETE: Removes records from a table

• CREATE TABLE: Creates a new table in the database

• ALTER TABLE: Modifies the structure of an existing table

• DROP TABLE: Deletes a table from the database

M language is a powerful data transformation language used in Power Query in Power BI.

• M language is used to transform and clean data in Power BI.

• It is a functional language with a wide range of functions and operators.

• M language is case-sensitive and uses a step-by-step approach to data transformation.

• Examples of M language functions include Table.TransformColumns and List.Transform.

Power BI offers different data connection modes including Import, DirectQuery, and Live Connection.

• Import mode: Data is imported into Power BI and stored in a local model.

• DirectQuery mode: Queries are sent directly to the data source in real-time.

• Live Connection mode: Power BI connects directly to the data source without importing data.

• Each mode has its own advantages and limitations based on data size, refresh frequency, and data source capabilities.

Our production deployment process involves thorough testing, version control, and collaboration with stakeholders.

• Create a deployment plan outlining steps and timelines

• Test changes in a staging environment before deploying to production

• Use version control to track changes and rollback if necessary

• Collaborate with stakeholders to ensure smooth deployment process

Data gateway is a tool that connects on-premises data sources with cloud-based applications.

• Data gateway allows for secure transfer of data between on-premises and cloud environments

• It acts as a bridge between on-premises data sources and cloud services like Power BI

• Data gateway helps in maintaining data security and compliance

• Examples of data gateways include Power BI Gateway and Azure Data Gateway

Import brings data into Power BI for processing, while direct query connects to data source live for real-time analysis.

• Import: Data is imported into Power BI for processing and analysis.

• Direct Query: Connects to data source live for real-time analysis without importing data.

• Import is suitable for smaller datasets, while direct query is better for large datasets or real-time analysis.

• Imported data is stored in Power BI file, while direct query does not store data locally.

• Impo...read more

DAX functions should be used appropriately and efficiently to achieve desired results.

• Understand the purpose and syntax of each DAX function

• Use the appropriate function for the specific calculation or analysis

• Avoid using too many nested functions as it can impact performance

• Test and validate the results of DAX functions before using them in production

• Document the DAX functions used in the Power BI report for future reference

Calculated columns are static values calculated at the row level, while measures are dynamic values calculated at the aggregate level.

• Calculated columns are stored in the data model and can be used in visuals directly.

• Measures are calculated on the fly based on the context of the visualization or report.

• Calculated columns are useful for creating new columns based on existing data, while measures are used for aggregations like sum, average, etc.

Use SUMX function in DAX to calculate total sales of a product

• Use SUMX function to iterate over each row in the sales table

• Filter the table to include only the specific product

• Sum up the sales amount for each row to get the total sales

PowerBI is a data visualization tool that helps users analyze and visualize data to make informed business decisions.

• PowerBI helps in creating interactive reports and dashboards

• It allows users to connect to various data sources like Excel, SQL databases, and cloud services

• Users can create custom visualizations and share insights with others

• PowerBI can be used for data exploration, data modeling, and data storytelling

Encrypted data is data that has been encoded or scrambled in such a way that only authorized parties can access and read it.

• Encrypted data is typically unreadable without the proper decryption key or algorithm

• Encryption helps protect sensitive information from unauthorized access or theft

• Examples of encrypted data include passwords, credit card numbers, and confidential documents

summarize is used to aggregate data at a specified level, while summarizetable is used to aggregate data across multiple tables.

• summarize is used with a single table, while summarizetable can be used with multiple tables

• summarize can only be used with columns from the specified table, while summarizetable can be used with columns from multiple tables

• summarize can be used to create new columns, while summarizetable is used to aggregate data

Use DAX function to shift one cell down in a table

• Use the LAG function in DAX to shift values down in a column

• Specify the number of rows to shift as a parameter in the LAG function

• Example: LAG([Column], 1) will shift values in 'Column' down by one row