Power BI

Q1: What is Power BI, and what are its key components?

Answer:
Power BI is a business intelligence (BI) and data visualization tool developed by Microsoft. It helps users connect to various data sources, transform data, create interactive reports, and share dashboards.

Key Components:

• Power BI Desktop
• Power BI Service (Power BI Online)
• Power BI Mobile
• Power BI Gateway
• Power BI Report Server

Q2: Explain the difference between Power BI Desktop and Power BI Service.

Answer:

Power BI Desktop

• Windows application
• Used to create reports and dashboards
• Supports data modeling and DAX
• Free to use

Power BI Service

• Cloud-based platform
• Used to publish, share, and collaborate on reports
• Supports scheduled refresh and workspaces
• Requires Power BI Pro/Premium for sharing

Q3: What are the main data connectivity options in Power BI?

Answer:
Power BI supports multiple data connectivity options including:

• Excel
• CSV Files
• SQL Server
• Oracle
• MySQL
• PostgreSQL
• Azure SQL Database
• SharePoint
• Salesforce
• Web APIs
• DirectQuery
• Live Connection
• Import Mode

Q4: What is Power Query, and what is its role in Power BI?

Answer:
Power Query is Power BI’s ETL (Extract, Transform, Load) tool.

It is used to:

• Import data
• Clean data
• Remove duplicates
• Merge tables
• Split columns
• Transform data before loading into Power BI

Q5: How can you create calculated columns and measures in Power BI?

Answer:

Calculated Column

• Created using DAX.
• Calculated row by row.
• Stored in the data model.

Measure

• Created using DAX.
• Calculated only when required.
• Used for aggregations and calculations in reports.

Q6: What is DAX, and what is its role in Power BI?

Answer:
DAX (Data Analysis Expressions) is the formula language used in Power BI.

It is used to:

• Create Measures
• Create Calculated Columns
• Create Calculated Tables
• Perform aggregations
• Implement Time Intelligence
• Build complex business calculations

Q7: How can you create relationships between tables in Power BI?

Answer:
Relationships are created using the Manage Relationships option.

Steps:

1. Open Model View.
2. Select Manage Relationships.
3. Choose matching columns between tables.
4. Define relationship type (One-to-One, One-to-Many, Many-to-Many).

Q8: What are slicers in Power BI, and how do they work?

Answer:
Slicers are visual filters that allow users to interactively filter report data.

They can filter by:

• Date
• Product
• Region
• Customer
• Category

Slicers automatically update all connected visuals on the report page.

Q9: How can you create a hierarchy in Power BI?

Answer:
A hierarchy is created by dragging one field onto another.

Example:

Year
   ↓
Quarter
   ↓
Month
   ↓
Day

Hierarchies allow users to drill down and drill up in reports.

Q10: Explain the difference between calculated columns and measures in Power BI.

Answer:

Q11: How can you create a custom visual in Power BI?

Answer:
Custom visuals can be created using the Power BI Visuals SDK with JavaScript and TypeScript.

You can:

• Build custom charts
• Import visuals from AppSource
• Publish custom visuals to the marketplace

Q12: What are the different types of filters in Power BI?

Answer:
Power BI supports four main types of filters:

• Visual-Level Filter
• Page-Level Filter
• Report-Level Filter
• Drill-through Filter

These filters help display only relevant data.

Q13: How can you schedule data refresh in Power BI?

Answer:
In Power BI Service:

1. Publish the report.
2. Open Dataset Settings.
3. Configure Data Source Credentials.
4. Enable Scheduled Refresh.
5. Set refresh frequency (Daily, Weekly, etc.).

Q14: Explain the difference between a report and a dashboard in Power BI.

Answer:

Q15: How can you share Power BI reports and dashboards with others?

Answer:
Reports can be shared by:

• Publishing to Power BI Service
• Sharing with specific users
• Creating Apps
• Embedding in websites
• Exporting to PDF or PowerPoint
• Sharing Workspace access

Q16: What is the Power BI Gateway, and when is it used?

Answer:
Power BI Gateway securely connects Power BI Service with on-premises data sources.

It is commonly used for:

• SQL Server
• Oracle
• Excel files
• On-premises databases

It supports scheduled refresh and DirectQuery.

Q17: How can you create a calculated table in Power BI?

Answer:
A calculated table is created using DAX.

Example:

Sales Summary =
SUMMARIZE(
    Sales,
    Sales[Region],
    "Total Sales", SUM(Sales[SalesAmount])
)

Q18: What is the difference between calculated columns and measures in terms of performance?

Answer:

Calculated Columns

• Increase model size.
• Consume memory.
• Calculated during data refresh.

Measures

• Do not consume storage.
• Calculated only when needed.
• Provide better report performance.

Q19: How can you implement Row-Level Security (RLS) in Power BI?

Answer:
Steps:

1. Open Manage Roles.
2. Create security roles.
3. Apply DAX filter expressions.
4. Publish the report.
5. Assign users to roles in Power BI Service.

RLS restricts users to view only authorized data.

Q20: How can you create a custom hierarchy in Power BI?

Answer:
To create a custom hierarchy:

1. Open Model View.
2. Right-click a column.
3. Select Create Hierarchy.
4. Add additional fields like Year, Quarter, Month, and Day.