QKS Group Postgresql DBA Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Medium

Started with project description, deep dive into project
Questions about ML, Statistics
Coding questions for Python, SQL

Q1. 
Stream of Characters Problem Statement
You are provided with a list, DICTIONARY[], which contains a collection of words, along with a stream of characters (queries). The task is to implement a class Chara...read more
Ans. 
Implement a class to check if a string formed by the last queried characters exists in a dictionary of words.
• Initialize the class with the dictionary of words.

• Implement a method to check if the string formed by the last queried characters exists in the dictionary.

• Use appropriate data structures to efficiently solve the problem.

• Ensure the class handles multiple test cases and character queries.

• Example: DICTIONARY[] = ['...read more
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Q2. How do you retrieve the second highest salary from a SQL database?
Ans. 
Use a subquery to retrieve the second highest salary from a SQL database.
• Use a subquery to select the maximum salary from the table.

• Then use another subquery to select the maximum salary that is less than the maximum salary found in the first step.

• Combine both subqueries to retrieve the second highest salary.
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Round duration - 60 minutes
Round difficulty - Easy

Projects
Machine Learning

Q1. Aptitude Questions
Questions about Statistics
Ans. 
Answering aptitude questions related to statistics
• Statistics is the study of collecting, analyzing, interpreting, presenting, and organizing data.

• Key concepts include mean, median, mode, standard deviation, and probability.

• Examples of statistical questions include 'What is the average income of a population?' and 'What is the likelihood of an event occurring?'
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Round duration - 60 minutes
Round difficulty - Easy

Behavioral Round
Questions asked about Amazon Leadership Principles

Round duration - 60 minutes
Round difficulty - Easy

Medium Python questions
Medium SQL questions

Q1. Ninja and Mathematics
Ninja is a genius in mathematics. He got an interview call from MIT. During the interview, the professor asked Ninja a challenging question.
Given two integers 'N1' and 'N...read more
Ans. 
Calculate the fraction when one integer is divided by another, with repeating decimal parts enclosed in parentheses.
• Divide the first integer by the second integer to get the fraction

• Identify if the fractional part is repeating and enclose it in parentheses

• Return the fraction for each test case
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Q2. How can you find the top 2 salaries for each department in SQL?
Ans. 
Use SQL query with window functions to find top 2 salaries for each department.
• Use PARTITION BY clause to partition the data by department.

• Use ORDER BY clause to order the salaries in descending order.

• Use ROW_NUMBER() function to assign a rank to each row within the partition.

• Filter the results to only include rows with rank 1 and 2.
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Medium to Hard 4 DSA questions

Related to codeing
Mathematical question

Q1. Questions based on SCM
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Q1. This is more of a vibe check about you. They will try to get to know you better. Questions related to your interest, expertise and your future plannings. This round is usually chill and it would mostly be ...read more
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