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Bhanu Bisht

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DBMS Interview Questions

Top questions asked at FAANG & product companies

DBMS Theory Questions

12 questions

EasyQ1

What is the difference between DBMS and RDBMS?

AmazonMicrosoftGoogle+2 more

MediumQ2

Explain ACID properties with examples.

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MediumQ3

What is Normalization? Explain 1NF, 2NF, 3NF.

OracleIBMAmazon+2 more

EasyQ4

What is the difference between DELETE, TRUNCATE, and DROP?

MicrosoftOracleInfosys+2 more

EasyQ5

What are different types of Keys in DBMS?

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MediumQ6

Explain different types of Joins with examples.

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MediumQ7

What is Indexing? When to use and when not to use?

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HardQ8

What is a Deadlock? How to prevent it?

AmazonMicrosoftOracle+2 more

HardQ9

Explain Transaction Isolation Levels.

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EasyQ10

What is a View? What are its advantages?

MicrosoftOracleSAP+2 more

MediumQ11

What is the difference between Clustered and Non-Clustered Index?

MicrosoftAmazonOracle+2 more

MediumQ12

Explain Relational Algebra operations.

GoogleAmazonMicrosoft+2 more

SQL Query Questions

12 questions

MediumQ1

Find the second highest salary from Employee table.

AmazonGoogleMicrosoft+2 more

EasyQ2

Write a query to find duplicate records in a table.

AmazonMicrosoftOracle+2 more

EasyQ3

Explain the difference between WHERE and HAVING.

AmazonMicrosoftGoogle+2 more

MediumQ4

Write a query to find employees who earn more than their manager.

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HardQ5

Explain Window Functions with examples.

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HardQ6

Find the top 3 highest paid employees in each department.

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MediumQ7

Write a query to delete duplicate rows keeping one.

AmazonMicrosoftOracle+2 more

EasyQ8

Explain the difference between UNION and UNION ALL.

MicrosoftOracleIBM+2 more

MediumQ9

Write a query to find cumulative/running total.

AmazonGoogleUber+2 more

EasyQ10

Find employees who joined in the last 30 days.

AmazonMicrosoftInfosys+2 more

HardQ11

Write a query to pivot rows to columns.

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HardQ12

Find customers who placed orders in consecutive days.

AmazonUberDoorDash+2 more

🎯 Interview Tips

DBMS Theory

• Know ACID with bank transfer example
• Practice normalizing tables to 3NF
• Understand indexing trade-offs
• Explain isolation levels clearly

SQL Queries

• Master window functions (ROW_NUMBER, RANK)
• Practice without IDE - use paper
• Know multiple approaches for same problem
• Understand query execution order

* Information based on publicly available data. Last reviewed: 2026.

🎯 Interview Tips

DBMS Theory

• Know ACID with bank transfer example
• Practice normalizing tables to 3NF
• Understand indexing trade-offs
• Explain isolation levels clearly

SQL Queries

• Master window functions (ROW_NUMBER, RANK)
• Practice without IDE - use paper
• Know multiple approaches for same problem
• Understand query execution order