Revolve Solutions Power BI Developer Interview Questions and Answers

Q1. Wat is cardinality
Ans. 
Cardinality refers to the uniqueness of values in a column or relationship.
• Cardinality is the number of unique values in a column or relationship.

• High cardinality means a column has many unique values, while low cardinality means few unique values.

• For example, a column like 'Customer ID' may have high cardinality, while 'Gender' may have low cardinality.
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Q2. Challenges faced
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Q1. Write SQL query
Ans. 
SQL query to retrieve data from a table
• Use SELECT statement to specify columns to retrieve

• Use FROM statement to specify the table to retrieve data from

• Use WHERE statement to filter the data based on conditions
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Power bi desktop in power bi service

Q1. What is power bi
Ans. 
Power BI is a business analytics tool by Microsoft that provides interactive visualizations and business intelligence capabilities.
• Power BI allows users to connect to various data sources and create interactive reports and dashboards.

• Users can easily share and collaborate on reports with others within the organization.

• It offers features like data modeling, data visualization, and data transformation.

• Power BI can be use...read more
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Q2. How creative a dashboard in power query
Ans. 
A creative dashboard in Power Query involves using unique visuals and interactive elements to present data in an engaging way.
• Utilize custom visuals to display data in a visually appealing manner

• Incorporate interactive elements such as slicers and filters for user-friendly navigation

• Use color coding and formatting to highlight important insights

• Include dynamic elements like tooltips and drill-down capabilities

• Experimen...read more
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Q1. Power bi desktop
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Q2. Write the Dax query in data modeling
Ans. 
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
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Q1. What is power pivot
Ans. 
Power Pivot is a data modeling tool in Excel that allows users to create relationships, calculations, and measures for analyzing large datasets.
• Power Pivot is an add-in for Excel that enables users to create data models and perform advanced data analysis.

• It allows users to import and combine data from multiple sources, create relationships between tables, and define calculations and measures.

• Users can create complex ca...read more
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Q2. Creation in dax
Ans. 
Creation in DAX refers to the process of generating new calculated columns or measures in Power BI using Data Analysis Expressions.
• Use DAX functions like CALCULATE, SUMX, AVERAGE, etc. to create new columns or measures

• Understand the data model and relationships to create accurate calculations

• Test the newly created calculations to ensure they are working correctly
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Q1. What are duplicates and references
Ans. 
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.
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Q2. How do you implement incremental refresh
Ans. 
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
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Q1. What is star schema and snowflake schema?
Ans. 
Star schema is a data warehouse schema where a central fact table is connected to multiple dimension tables. Snowflake schema is a normalized form of star schema.
• Star schema consists of a central fact table connected to multiple dimension tables

• Snowflake schema is a normalized form of star schema where dimension tables are further normalized into sub-dimension tables

• Star schema is denormalized for faster query performa...read more
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Q2. Explain about your experience in SQL joins
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Q3. Tell me what ways you improve performance of report?
Ans. 
Performance of reports can be improved by optimizing queries, reducing data volume, using efficient visuals, and caching data.
• Optimize queries by removing unnecessary columns and filters

• Reduce data volume by aggregating data at the source or using incremental refresh

• Use efficient visuals like matrix instead of tables for large datasets

• Cache data to reduce query times for frequently accessed data
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Q4. What is data query and data flow?
Ans. 
Data query is the process of retrieving specific data from a database, while data flow is the movement of data from one point to another.
• Data query involves writing SQL queries to extract specific data from a database

• Data flow refers to the movement of data from source to destination through various transformations

• Data query is used to filter and retrieve relevant data, while data flow ensures data is processed and mov...read more
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Q5. Difference between power query and direct query
Ans. 
Power Query is used to import and transform data within Power BI, while Direct Query allows real-time data access from the data source.
• Power Query is used to import and transform data within Power BI before loading it into the data model.

• Direct Query allows Power BI to query the data source directly in real-time, without importing the data into the data model.

• Power Query is suitable for smaller datasets that can be loa...read more
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Q6. What is RANK & DENSE RANK in SQL
Ans. 
RANK assigns a unique rank to each row based on a specified column, while DENSE RANK assigns a unique rank to each distinct row.
• RANK function is used to assign a unique rank to each row based on a specified column

• DENSE RANK function is used to assign a unique rank to each distinct row, skipping ranks if there are ties

• RANK and DENSE RANK are commonly used in SQL queries to rank data based on certain criteria
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Q7. What is Calculated column and Measure?
Ans. 
Calculated column is a static column in a table calculated based on a formula, while Measure is a dynamic calculation based on aggregated data.
• Calculated column is created in Power BI using DAX formula and stored in the data model.

• Measure is a calculation performed on the fly based on the context of the visualization.

• Calculated columns are static and can be used for filtering and sorting, while Measures are dynamic and
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Q8. Tell me about complex DAX functions you used
Ans. 
I have used complex DAX functions like CALCULATE, FILTER, SUMX, etc. to perform advanced calculations in Power BI.
• Used CALCULATE function to apply filters and context changes to calculations

• Utilized FILTER function to filter data based on specific conditions

• Implemented SUMX function to iterate over a table and perform calculations for each row
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Q9. What is CALCULATED function and how it works?
Ans. 
CALCULATED function is used in Power BI to create custom calculations based on existing data in a report.
• CALCULATED function is used to create custom calculations in DAX (Data Analysis Expressions) language.

• It allows users to define complex calculations based on existing data in the report.

• CALCULATED function can be used with other DAX functions to perform calculations like aggregations, comparisons, and conditional lo...read more
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Q10. What is query folding in power BI?
Ans. 
Query folding in Power BI is a process where Power BI pushes the data transformation steps back to the data source.
• Query folding improves performance by reducing the amount of data loaded into Power BI.

• It allows Power BI to leverage the capabilities of the data source for data transformation.

• Commonly used with relational databases like SQL Server, Oracle, etc.

• Example: When filtering data in Power BI, query folding will...read more
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Q11. Tell me about types of Context
Ans. 
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
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Q12. Fundamentals of POWER BI?
Ans. 
Power BI is a business analytics tool by Microsoft that provides interactive visualizations and business intelligence capabilities.
• Power BI is a business analytics tool by Microsoft

• It allows users to create interactive visualizations and reports

• Users can connect to various data sources to import data

• Power BI offers a wide range of data visualization options such as charts, graphs, and maps

• Users can share and collaborat
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Q13. DDL & DML commands?
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Q14. Give me an example forINNER JOIN in sql
Ans. 
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.Cus
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Q1. What are the components of Power bi
Ans. 
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.
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Q2. What is mean by DAX
Ans. 
DAX stands for Data Analysis Expressions and is a formula language used in Power BI for creating custom calculations.
• DAX is used to create custom calculations in Power BI, similar to Excel formulas.

• It can be used to create calculated columns, measures, and calculated tables.

• DAX functions can be used to manipulate data, perform calculations, and create complex expressions.

• Examples of DAX functions include SUM, AVERAGE,
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Q3. What is mean by M language
Ans. 
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.
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It was a real-time scenario that they asked about.

Q1. Without RLS how can you implement the security to data?
Ans. 
Implement security to data using row-level security (RLS)
• Use user roles and permissions to restrict access to specific data

• Leverage Power BI's built-in security features such as dataset security and data categorization

• Implement dynamic security based on user context or attributes

• Utilize Power BI's security features like Azure Active Directory integration for authentication and authorization
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Q1. Difference between import and direct query
Ans. 
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...read more
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