Quess Power BI Developer Interview Questions and Answers

The DAX formula for calculating a running total is using the CALCULATE function with the FILTER function.

• Use the CALCULATE function to evaluate an expression in a context modified by filters.

• Use the FILTER function to return a table that represents a subset of another table or expression.

• Combine CALCULATE and FILTER functions to calculate a running total.

The DAX formula for replacing blank values with zero and vice versa is IF(ISBLANK(), 0, BLANK())

• Use the IF function in DAX to check if a value is blank

• If the value is blank, return 0. If not, return blank()

SQL queries are essential for data manipulation and retrieval in Power BI, enabling effective data analysis.

• Use SELECT statements to retrieve data: e.g., SELECT * FROM Patients;

• Implement JOINs to combine data from multiple tables: e.g., SELECT a.Name, b.Diagnosis FROM Patients a JOIN Diagnoses b ON a.ID = b.PatientID;

• Utilize WHERE clauses for filtering data: e.g., SELECT * FROM Appointments WHERE Date > '2023-01-01'...read more

I have 3 years of experience as a Power BI Developer in a consulting firm.

• Developed interactive dashboards and reports using Power BI

• Worked closely with business stakeholders to gather requirements

• Optimized data models for performance and efficiency

SUM calculates the total of a column, while SUMX evaluates an expression for each row in a table and returns the sum of the results.

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

• SUMX is used to iterate over each row in a table, evaluate an expression, and return the sum of the results.

• SUMX is commonly used in DAX formulas to perform calculations row by row.

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 envir...read more

Row level security is a feature in Power BI that restricts access to data at the row level based on user roles or criteria.

• Row level security allows you to control which rows of data a user can see in a report or dashboard.

• It is commonly used to ensure that users only see the data that is relevant to them based on their role or department.

• Row level security can be implemented using DAX expressions to filter data based ...read more