Cognizant

Cognizant

American multinational information technology services and consulting company.

4 Rounds ~21 Days Medium
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The Interview Loop

Recruiter Screen (30 min)

Standard fit check, behavioral questions, and resume overview.

Technical Loop (3-4 Rounds)

Deep dive into domain knowledge, coding, and system design.

Interview Question Bank

Backend Engineer • Coding • easy

Write a SQL query to find the second highest salary of an employee from an Employee table.

#Database #Queries
Practice
Backend Engineer • Coding • medium

Write a SQL query to find duplicate records in a table based on a specific column, and return the count of duplicates.

#Database #Group By #Having
Practice
Backend Engineer • Technical • medium

What is the difference between Clustered and Non-Clustered Indexes in a relational database?

#Database #Indexing #Performance
Practice
Backend Engineer • Technical • medium

How do you approach optimizing a slow-running query in PostgreSQL or Oracle?

#Performance Tuning #Execution Plan
Practice
Data Engineer • Coding • medium

Write a SQL query to find the cumulative sum of sales per day for the current month.

#Window Functions #Aggregations #Date Functions
Practice
Data Engineer • Coding • medium

Write a SQL query to delete duplicate rows from a table, keeping only the record with the lowest ID.

#Data Cleaning #CTEs #DELETE
Practice
Data Engineer • Coding • easy

Write a SQL query to find all employees who earn more than their direct managers. The table 'Employee' has columns: Id, Name, Salary, ManagerId.

#Self Join #Filtering
Practice
Data Engineer • Coding • medium

Write a SQL query to find the top 3 highest earning employees in each department, handling ties appropriately.

#Window Functions #DENSE_RANK #PARTITION BY
Practice
Data Engineer • Technical • easy

What is the difference between a Left Join and an Inner Join? What happens to the result set if the right table has multiple matching rows for a single row in the left table?

#Joins #Data Duplication
Practice
Data Engineer • Technical • easy

Explain the difference between ROW_NUMBER(), RANK(), and DENSE_RANK(). In what client reporting scenario would you choose DENSE_RANK over RANK?

#Window Functions #Data Analysis
Practice
Data Scientist • Coding • medium

Write a SQL query to find the second highest salary within each department from an Employee table. How would you handle ties?

#Window Functions #DENSE_RANK #Data Aggregation
Practice
Data Scientist • Coding • medium

For a retail client, we need to calculate the 7-day rolling average of daily sales. Write the SQL query to achieve this.

#Window Functions #Time Series #Moving Averages
Practice
Data Scientist • Coding • medium

Given a table of customer transactions, write a query to identify 'churned' customers, defined as those who made a purchase in the last 6 months but not in the last 30 days.

#Filtering #Date Functions #Conditional Logic
Practice
Data Scientist • Technical • easy

Explain the difference between RANK, DENSE_RANK, and ROW_NUMBER. Give a business scenario where you would use each.

#Window Functions #Ranking
Practice
Machine Learning Engineer • Coding • easy

Write a SQL query to find the second highest salary from an Employee table. How would you modify this to find the Nth highest salary?

#SQL #Subqueries #Window Functions
Practice
Machine Learning Engineer • Coding • medium

Write a SQL query to calculate a 7-day rolling average of daily sales for a retail client.

#SQL #Window Functions #Time Series Data
Practice
Product Manager • Coding • easy

Write a SQL query to find the top 3 most active users by transaction volume in the last 30 days for a fintech application.

#Data Analysis #SQL #Product Metrics
Practice
Product Manager • Coding • medium

Write a SQL query to calculate the month-over-month retention rate of users on a subscription platform.

#Retention #Advanced SQL #Product Metrics
Practice
Software Engineer • Technical • medium

Write a SQL query to find the nth highest salary from an Employee table.

#SQL Queries #Subqueries #Window Functions
Practice
Software Engineer • Technical • medium

Write a SQL query to fetch all employees who are also managers (using a self-join).

#SQL Queries #Joins
Practice

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Senior Engineer

Focuses on core competencies, system constraints, and clear communication.

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Think Out Loud

Always explain your thought process before writing code or drawing architecture.

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