MASAI School Data Analyst Interview Questions and Answers

Q1. SQL question difference between having and where
Ans. 
HAVING is used with GROUP BY to filter groups, WHERE is used to filter rows
• HAVING is used with GROUP BY to filter groups based on aggregate functions

• WHERE is used to filter rows based on conditions

• HAVING is applied after GROUP BY, WHERE is applied before GROUP BY

• Example: SELECT department, AVG(salary) FROM employees GROUP BY department HAVING AVG(salary) > 50000;

• Example: SELECT * FROM employees WHERE department = 'S
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Q1. How would you use your skill for sales
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Q1. What is DAX and its use in power bi
Ans. 
DAX (Data Analysis Expressions) is a formula language used in Power BI for data modeling and analysis.
• DAX is used to create calculated columns and measures in Power BI.

• It allows for advanced data analysis, such as time intelligence functions (e.g., YEAR, MONTH).

• Example: A measure to calculate total sales could be defined as: Total Sales = SUM(Sales[Amount]).

• DAX supports filtering and context manipulation, enabling dyna...read more
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Q2. Role of power query in power bi
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2 coding questions with aptitude question(logical aptitude and quantitative aptitude)

This was a Machine Coding. We need to design a system and then they will check our design by running test cases. It was 2.5 hrs long.

Q1. Basic questions on computer core subjects(Deadlock, Networking, Tcp connection, process scheduling etc, DNS Lookup etc)
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Q2. Questions on React, Node and the libraries which I used in my project(My project was a full stack project)
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Q1. What is OOPS concepts.
Ans. 
OOPS concepts refer to Object-Oriented Programming principles like inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation detail
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Q2. What is PDO and uses in PHP.
Ans. 
PDO stands for PHP Data Objects, a database access layer providing a uniform method of access to multiple databases.
• PDO is a PHP extension that provides a data-access abstraction layer.

• It supports multiple database systems like MySQL, PostgreSQL, SQLite, etc.

• PDO helps prevent SQL injection attacks by using prepared statements.

• It allows for error handling and supports transactions.

• Example: $pdo = new PDO('mysql:host=loc...read more
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Q1. Find duplicates in an array
Ans. 
Use a hash set to find duplicates in an array of strings.
• Create a hash set to store unique elements.

• Iterate through the array and check if the element is already in the hash set.

• If it is, then it is a duplicate. If not, add it to the hash set.
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Q2. Find single duplicate element in an array where contents of the array are length of array - 1
Ans. 
Find the single duplicate element in an array of strings with length n-1.
• Iterate through the array and use a HashSet to keep track of elements seen so far.

• If an element is already in the HashSet, that is the duplicate element.

• Return the duplicate element once found.
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Create a student support system

Q1. Design an order and payments system for an EdTech company
Ans. 
Design an order and payments system for an EdTech company
• Allow users to browse and select courses

• Implement a shopping cart for users to add courses

• Integrate payment gateways for secure transactions

• Provide order confirmation and receipt to users

• Allow users to track their order status
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Basic coding and MySQL queries. Like Types of join, having and where difference etc.

Q1. Salary Discussion.
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