Interview questions
Preparing for a data engineering interview at Cognizant? This page contains 14 real interview questions sourced from verified Cognizant interview experiences. Questions are sorted by frequency — the ones asked most often appear first.
Cognizant data engineering interviews typically focus on SQL, System Design/Architecture, and Behavioral. The interview bar skews toward harder problems (6 hard vs. 3 easy), suggesting emphasis on depth and system-level thinking.
Use the difficulty filters above to focus your preparation. For each question, attempt your own answer first, then compare with our expert solution. You can also practice these questions in our AI Mock Interview Coach for real-time feedback.
Write an SQL query to find the second-highest salary from an employee table.
What architecture are you following in your current project, and why?
Can you explain the difference between OLTP and OLAP?
Explain the concept of ACID properties in the context of databases.
Explain the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.
How do you handle NULL values in SQL? Mention functions like COALESCE and NULLIF.
What is a Common Table Expression (CTE), and when would you use it?
What is the difference between a primary key and a unique key?
What is the difference between WHERE and HAVING clauses in SQL?
What is the most difficult task you've ever worked on?
Business generates TBs of data daily. How would you design the data pipeline in Azure?
Given a string 'AAAVGXFHHFSGFGGLK', find the non-repeating letters.
What are Spark optimizations, and can you explain them?
How would you process Excel files with multiple sheets? Design the data pipeline.
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