NielsenIQ Interview Questions and Answers for Experienced

Q1. Write MySQL query to find employee with 2nd Highest salary
Ans. 
Use MySQL query with ORDER BY and LIMIT to find employee with 2nd highest salary.
• Use ORDER BY salary DESC to sort salaries in descending order

• Use LIMIT 1,1 to skip the highest salary and get the second highest salary
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Q2. What is branch in git
Ans. 
A branch in git is a separate line of development that allows you to work on features or fixes without affecting the main codebase.
• Branches allow for parallel development

• They can be created, switched between, merged, and deleted

• Common branches include master, develop, feature branches, and release branches
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Q1. What is stored procdedure?
Ans. 
Stored procedure is a precompiled collection of SQL statements that can be executed by calling the procedure name.
• Stored procedures are used to encapsulate and group SQL code for reuse and performance optimization.

• They can accept input parameters and return output parameters.

• Stored procedures can be called from applications or other stored procedures.

• They are stored in the database and can be executed multiple times wi...read more
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Q2. What are the joins
Ans. 
Joins are used in databases to combine rows from two or more tables based on a related column between them.
• Joins are used to retrieve data from multiple tables based on a related column between them

• Common types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• INNER JOIN returns rows when there is at least one match in both tables

• LEFT JOIN returns all rows from the left table and the matched rows from th...read more
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Q1. How will you cleanup disk
Ans. 
To cleanup disk, you can use disk cleanup tools, delete unnecessary files, uninstall unused programs, and empty the recycle bin.
• Use disk cleanup tools like Disk Cleanup in Windows or CleanMyMac in macOS to remove temporary files and other unnecessary data

• Delete unnecessary files and folders that are taking up space on the disk

• Uninstall unused programs or applications to free up disk space

• Empty the recycle bin to perman...read more
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Q2. Daily BAU activities
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Q1. Basic java and selenium questions. Oops concept, singleton class, diff b/w interface and abstract Exception, broken links, find element and find elements. Very basic interview questions
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Q2. Basic Api and sql query
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Q1. Agile methodology
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Q1. Work experience and salary
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Online coding test with spring boot rest API and a java problem solving.

Q1. Design a REST API
Ans. 
Design a REST API for a backend Java developer
• Define the resources and endpoints

• Use HTTP methods like GET, POST, PUT, DELETE

• Implement authentication and authorization

• Use JSON for data exchange

• Include error handling and status codes
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Q2. Provided a list of string with names. and the result should be with a map of the name as key and number of vovels as value. Use Java stream API only.
Ans. 
Use Java Stream API to create a map of names and their corresponding vowel counts.
• Use Stream.of() to create a stream from the array of names.

• Map each name to its vowel count using a custom method.

• Collect the results into a Map using Collectors.toMap().

• Example: For names ['Alice', 'Bob'], the output would be {'Alice': 3, 'Bob': 1}.
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Q1. Difference between list and set
Ans. 
List is an ordered collection of elements with duplicates allowed, while set is an unordered collection of unique elements.
• List maintains the order of elements, while set does not guarantee any specific order.

• List allows duplicate elements, while set does not allow duplicates.

• Example: List - [1, 2, 3, 1], Set - {1, 2, 3}
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Q2. How to optimize pyspark
Ans. 
Optimizing PySpark involves tuning configurations, using efficient transformations/actions, and leveraging caching.
• Tune PySpark configurations for optimal performance (e.g. adjusting memory settings, parallelism)

• Use efficient transformations/actions to minimize unnecessary data shuffling (e.g. using narrow transformations like map instead of wide transformations like groupByKey)

• Leverage caching to persist intermediate ...read more
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Q3. Explain SOLID principles
Ans. 
SOLID principles are a set of five design principles in object-oriented programming to make software designs more understandable, flexible, and maintainable.
• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable...read more
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