Infosys DBMS Technical Interview Questions and Answers

Cracking an Infosys technical interview requires a solid grip on Database Management Systems (DBMS). While programming and problem-solving play a big role, DBMS is one of those subjects where even a small conceptual slip can cost you the opportunity. Having appeared for and guided others through Infosys interview rounds, I’ve put together a complete guide of commonly asked Infosys DBMS technical interview questions and answers.

This is not just a set of definitions — it’s a collection of practical explanations, examples, and interview-ready answers that you can revise quickly before facing the panel.

1. Basic DBMS Questions

Q1. What is DBMS?
A DBMS is software that helps in storing, managing, and retrieving data in a systematic way. Instead of files scattered here and there, DBMS provides a centralized solution where data is consistent, secure, and easier to query. Popular examples are MySQL, Oracle, and SQL Server.

Q2. What are the main types of DBMS?

• Hierarchical DBMS – Organizes data in a tree-like structure.

• Network DBMS – Uses a graph structure with many-to-many relations.

• Relational DBMS – Stores data in tables (the most widely used).

• Object-Oriented DBMS – Stores objects along with attributes and methods.

Q3. How is RDBMS different from DBMS?

• DBMS manages data in general, without strict relationships.

• RDBMS specifically organizes data into tables and maintains relationships through keys. For Infosys interviews, mentioning primary key and foreign key differences will strengthen your answer.

Q4. What is a primary key?
It uniquely identifies every row in a table. It cannot be NULL or duplicated. For instance, in an employee table, EmployeeID is usually the primary key.

Q5. What is a foreign key?
A foreign key is a column that refers to the primary key in another table, ensuring referential integrity. Example: DepartmentID in Employee table pointing to DepartmentID in Department table.

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2. Intermediate DBMS Questions

Q6. What is normalization? Why is it important?
Normalization is the process of structuring data to reduce redundancy and improve data integrity.

• 1NF: Keep data atomic, remove repeating groups.

• 2NF: Remove partial dependency.

• 3NF: Remove transitive dependency.

• BCNF: Every determinant must be a candidate key.

Infosys interviewers often ask: “Give me an example where normalization is applied.” Be ready with a scenario like splitting customer and order data into separate tables.

Q7. What is denormalization?
The opposite of normalization. Sometimes, for performance reasons, redundancy is deliberately introduced. This is common in reporting systems where query speed matters more than storage optimization.

Q8. What are indexes?
Indexes speed up data retrieval.

• Clustered index sorts data physically in the table.

• Non-clustered index creates a logical pointer to data.

Q9. Explain DELETE vs TRUNCATE vs DROP.

• DELETE → Removes selected rows, can be rolled back.

• TRUNCATE → Clears entire table, faster, cannot use WHERE.

• DROP → Removes table structure and data permanently.

Q10. What are transactions and ACID properties?
Transactions are logical units of work. ACID ensures:

• Atomicity → All or nothing.

• Consistency → Rules are not broken.

• Isolation → Transactions don’t interfere.

• Durability → Changes are permanent once committed.

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3. Advanced DBMS Questions

Q11. What is a deadlock? How do you resolve it?
Deadlock happens when two transactions wait for each other indefinitely.
Ways to handle:

• Prevention (resource ordering, timeout).

• Detection (wait-for graph cycle check).

• Recovery (abort one transaction).

Q12. What is the difference between OLTP and OLAP?

• OLTP (Online Transaction Processing) → Day-to-day small transactions, e.g., banking systems.

• OLAP (Online Analytical Processing) → Complex queries and reporting, e.g., business intelligence dashboards.

Q13. What are triggers?
A trigger is an automatic action that runs when certain events happen (like insert, update, delete). For example, auto-logging changes to a user table.

Q14. Stored Procedure vs Function?

• Stored Procedure → Can perform multiple tasks, may or may not return a value, supports transactions.

• Function → Must return a single value, used within queries.

Q15. What are different types of joins?

• INNER JOIN → Common records in both tables.

• LEFT JOIN → All from left + matches from right.

• RIGHT JOIN → All from right + matches from left.

• FULL JOIN → All records from both tables.

• CROSS JOIN → Cartesian product.

• SELF JOIN → Table joined with itself.

Q16. What is concurrency control?
It ensures multiple transactions can happen together without corrupting data. Common methods:

• Locking (shared/exclusive).

• Timestamp ordering.

• Optimistic concurrency.

Q17. What is sharding in databases?
Sharding is horizontal partitioning of data across multiple servers. Large applications like social media use sharding to scale.

Q18. How do you ensure database security?

• Strong authentication & access control.

• Role-based privileges.

• Data encryption.

• Backup and recovery policies.

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Final Thoughts

Infosys interviewers often focus on how well you apply DBMS concepts to real-world scenarios rather than just textbook answers. If you can explain with examples like banking systems for ACID properties, e-commerce for normalization, or social media for sharding, you’ll stand out.

If you’re preparing for Infosys, I recommend revising queries (especially JOINs and subqueries), practicing normalization problems, and brushing up on indexing and transactions. DBMS is not about mugging up — it’s about showing that you can manage data efficiently and logically.