Zelis Data Engineer Interview Questions and Answers

Q1. How do you delete duplicate values
Ans. 
To delete duplicate values, use SQL queries with DISTINCT keyword or programming languages like Python with sets.
• In SQL, use SELECT DISTINCT to retrieve unique values

• In Python, convert list to set to automatically remove duplicates

• Use pandas library in Python to drop duplicates in a DataFrame
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Asked few questions on sql asked to write query for problem given on spot

Q1. Internal external tables
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Q2. MySQL questions
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Q1. Question on sql and other stuff
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Q1. Question on sql and other stuff
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Q1. Question on sql and queries
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Leetcode questions easy to medium level

Q1. Project explanation
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Q2. 2nd highest salary in sql / pyspark
Ans. 
To find the 2nd highest salary in SQL or PySpark, use the ORDER BY and LIMIT clauses.
• Use ORDER BY clause to sort the salaries in descending order

• Use LIMIT 1,1 to get the second highest salary
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Q1. Salary negotiation
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Q2. Why you want to join Visa
Ans. 
I want to join Visa because of its reputation as a global leader in payment technology and innovation.
• Visa's reputation as a global leader in payment technology and innovation aligns with my career goals.

• I am excited about the opportunity to work on cutting-edge data engineering projects at Visa.

• I believe that joining Visa will provide me with the chance to collaborate with talented professionals in the industry.

• Visa's...read more
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Interview: resume,puzzles, guesstimates

1 hr medium level DSA questions

Q1. DFS in tree Data Structure
Ans. 
DFS (Depth First Search) is a traversal algorithm used in tree data structures to explore as far as possible along each branch before backtracking.
• DFS starts at the root node and explores as far as possible along each branch before backtracking.

• It uses a stack to keep track of nodes to visit next.

• DFS can be implemented recursively or iteratively.

• Example: In a binary tree, DFS would visit the left child of a node before
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Q2. SQL normalisation types and explanation
Ans. 
SQL normalisation types include 1NF, 2NF, 3NF, BCNF, and 4NF, each with specific rules for eliminating data redundancy.
• 1NF (First Normal Form) - Each column in a table must contain atomic values, and there should be no repeating groups.

• 2NF (Second Normal Form) - Table should be in 1NF and all non-key attributes should be fully functionally dependent on the primary key.

• 3NF (Third Normal Form) - Table should be in 2NF an...read more
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Q1. Preferred Location
Ans. 
I am open to opportunities in various locations, depending on the job offer and company culture.
• Open to relocation for the right opportunity

• Prefer locations with good work-life balance

• Interested in cities with strong tech communities
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Q2. About the company
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