Top 10 Power BI interview questions with answers:

1. What are the key components of Power BI?

Solution:

Power Query: Data transformation and preparation.

Power Pivot: Data modeling.

Power View: Data visualization.

Power BI Service: Cloud-based sharing and collaboration.

Power BI Mobile: Mobile reports and dashboards.

2. What is DAX in Power BI?

Solution:
DAX (Data Analysis Expressions) is a formula language used in Power BI to create calculated columns, measures, and tables.
Example:

TotalSales = SUM(Sales[Amount])

3. What is the difference between a calculated column and a measure?

Solution:

Calculated Column: Computed row by row in the data model.

Measure: Computed at the aggregate level based on filters in a visualization.

4. How do you connect Power BI to a database?

Solution:

1. Open Power BI Desktop.


2. Go to Home > Get Data > Database (e.g., SQL Server).


3. Enter server and database details, then load or transform data.

5. What is the role of relationships in Power BI?

Solution:
Relationships define how tables in a data model are connected. Power BI uses relationships to filter and calculate data across multiple tables.

6. What are slicers in Power BI?

Solution:
Slicers are visual filters that allow users to interactively filter data in reports.
Example: A slicer for "Region" lets users view data specific to a selected region.

7. How do you implement Row-Level Security (RLS) in Power BI?

Solution:

1. Define roles in Modeling > Manage Roles.


2. Use DAX expressions to restrict data (e.g., [Region] = "North").


3. Assign roles to users in the Power BI Service.

8. What are the different types of joins in Power BI?

Solution:
Power BI offers the following join types in Power Query:

Inner Join

Left Outer Join

Right Outer Join

Full Outer Join

Anti Join (Left/Right Exclusion)

9. What is the difference between Power BI Pro and Power BI Premium?

Solution:

Power BI Pro: Allows sharing and collaboration for individual users.

Power BI Premium: Provides dedicated resources, larger dataset sizes, and supports enterprise-level usage.

10. How can you optimize Power BI reports for performance?

Solution:

- Use summarized datasets.

- Reduce visuals on a single page.

- Optimize DAX expressions.

- Enable aggregations for large datasets.

- Use query folding in Power Query.

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