WNS Power BI Developer Interview Questions and Answers

Power BI consists of various components that facilitate data visualization, analysis, and sharing insights effectively.

• Power BI Desktop: A Windows application for creating reports and dashboards.

• Power BI Service: A cloud-based service for sharing and collaborating on reports.

• Power BI Mobile: Mobile apps for accessing reports on smartphones and tablets.

• Power Query: A data connection technology for importing and transfor...read more

Data modeling in Power BI involves structuring data to create meaningful insights and relationships for effective reporting.

• Star Schema: A common modeling technique where a central fact table is connected to multiple dimension tables, e.g., sales data linked to product and customer dimensions.

• Relationships: Establishing relationships between tables using primary and foreign keys, such as linking a 'CustomerID' in a sal...read more

RLS in Power BI restricts data access based on user roles, enhancing security and data privacy.

• Row-Level Security (RLS) can be implemented using DAX filters to restrict data access.

• There are two types of RLS: Static RLS and Dynamic RLS.

• Static RLS involves defining roles and permissions manually, e.g., a role for 'Sales Managers' to see only their region's data.

• Dynamic RLS uses user attributes to filter data automatical...read more

Create a Power BI dashboard using measures and data from an Excel dataset to visualize QC and error metrics.

• Measures Creation: Calculate QC%, Internal Error%, and External Error% using DAX formulas based on the provided dataset.

• Dropdowns: Implement slicers for month and process to filter data dynamically on the dashboard.

• Card Visuals: Use card visuals to display key metrics like QC%, Internal Error%, and Internal Accur...read more

Power BI Report is a single report page, while Power BI App is a collection of multiple reports and dashboards.

• Power BI Report is a single page report with visualizations and data insights.

• Power BI App is a collection of multiple reports, dashboards, and datasets organized together.

• Power BI Report can be shared individually, while Power BI App is shared as a package of related content.

• Power BI App allows for more inter...read more

Key concepts and challenges in Power BI development, including relationships, schemas, joins, and data manipulation techniques.

• Challenges in projects may include data quality issues, performance optimization, and user adoption.

• Active relationships are used in calculations, while inactive relationships can be activated using DAX functions like USERELATIONSHIP.

• Star schema has a central fact table connected to dimension t...read more

Yes, relocation is possible in various contexts, including jobs, homes, and data management.

• Relocation in job context: Employees may move to different offices or cities for work.

• Relocation in data management: Power BI allows users to relocate datasets and reports to different workspaces.

• Relocation in personal life: Individuals often relocate for better living conditions or job opportunities.

SUM calculates the sum of a column or expression, while SUMX calculates the sum of an expression evaluated for each row in a table.

• SUM is used to calculate the sum of a column or expression in Power BI.

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

• SUM is typically used with columns, while SUMX is used with tables or filtered tables.

• SUMX can be used to perform more complex calculat...read more

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%.

Interaction mode in Power BI allows users to interact with visualizations and explore data in a more dynamic way.

• Interaction mode can be accessed by clicking on the 'Focus mode' button in the top right corner of a visualization.

• In interaction mode, users can hover over data points to see more information, filter data, and drill down into details.

• Users can also use the 'Selection pane' to show or hide specific visualiza...read more

Power BI has various types of filters such as visual, page, report, drill-through, and slicer filters.

• Visual filters apply to a single visual or chart.

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

• Report filters apply to all visuals in a report.

• Drill-through filters allow users to navigate to more detailed data.

• Slicer filters allow users to filter data across multiple visuals.

Schema for n Power BI is the structure of the data model used to organize and connect data sources.

• Schema defines the relationships between tables, columns, and measures.

• It helps in creating a logical model of the data.

• Schema can be created using Power BI Desktop or Power BI Service.

• Example: A schema for sales data may include tables for customers, products, and sales transactions.

• Schema can also include calculated col...read more