Power BI Interview Preparation Notes:

1. What is power bi?
   Power Bi is a BUSINESS INTELLIGENCE(BI) and DATA VISUALIZATION tool developed by MICROSOFT. It helps user turn raw data into meaningful reports and interactive dashboards. With Power Bi businesses can easily understand their data and make better decisions.

2. what is bi?
   BI stand for BUSINESS INTELLIGENCE. It helps businesses collect, analyse, and visualize data to make better decisions.

3. what are the main components of power bi?

   1. Power bi Desktop - used to create reports and dashboard
   2. Power bi Service - Used to publish and share reports
   3. Power bi Mobile - Used to view reports on mobile devices online.
   4. Power bi Report Server - Used to store reports on a company's own server.

4.What is power bi desktop?

Power bi desktop is a free application provided by Microsoft.
It is mainly used to import data, clean the data using power query, create relationships, build chart, and design dashboards.
After completing the report we can publish it to power bi service.

5.what is a dashboard?

A dashboard is a single page that shows the most important business information.
It contains visuals like KPL cards, charts, and graphs.
Dashboards help used quickly understand business performance.

6.What is a report?

A report is a collection of one or more pages that contain charts, tables, slicers, and other visuals. Reports allow users to analyze data in detail and interact with the visuals.

7.What is a dataset?

A dataset is a collection of data that is imported into power bi. The data can come from Excel, CSV files, SQL Server, or other data sources. Power bi used the dataset to create reports and dashboards.

8.What are the data sources supported by power bi?

Power bi supports many data sources, such as:

1. Excel
2. CSV
3. SQL Server
4. MySQL
5. Oracle
6. SharePoint
7. Web
8. Azure We can connect to these sources and analyze the data.

9.What is power query?

power query is tool used to clean and transform data before loading it into power bi.

USING POWER QUERY, we can:

• Remove duplicate values
• Remove null values
• Change data types
• Rename columns
• Filter rows
• Merge or split columns this helps improve the quality of the data.

10.What is DAX?

DAX stands for DATA ANALYSIS EXPRESSIONS.
It is a formula language used in power bi.

DAX is used to create:
DAX stands for DATA ANALYSIS EXPRESSIONS.

DAX is used to create:

1. Measures (TBD).

2. Calculated Columns.
   3.Calculated Tables.

   It helps us perform calculation like total sales, average,
   profit, percentage and more.

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

A calculated column calculates values for each row and store the result in the table.
A measure calculates values only when needed in a visual and is not store in the table.
Measures use less memory and are commonly used in reports.

12.What is a relationships?

A relationship is used to connect two or more tables using a common column.
For example, we can connect the product id in one table with the product id in another table.
Relationships help us analyze data from multiple tables together.

13.What are the types of relationships?

Power bi supports four types of relationships:
1. one-to-one
2. one-to-many
3. many-to-one
4. many-to-many
The most commonly used relationship is ONE-TO-MANY

examples:
one-to-one:

one-to-many:
Customer Table:

Explanation:
One customer can place many orders, but each order belongs to only one customer.

MANY-TO-ONE:
Orders Table:

Explanation:
Many orders can have the same product, but each Product ID in the Orders table points to one product in the Products table.

MANY-TO-MANY:

Students Table:

1. What is a Slicer?

A Slicer is a filtering tool in power bi.

it allows users to filter report data by selecting values such as category, year, or region.

Slicers make reports interactive and easy to use.

1. What is KPI?

KPI stands for KEY PERFORMANCE INDICATOR. It is used to measure the performance of a business or project. In power bi, KPI visuals display important values such as Total Sales, Total Profit, Total Orders, and Average Rating. KPIs help users quickly understand business performance and make better decisions.