Amazon SQL Interview Questions 2025

Amazon SQL Interview Questions: A Comprehensive Guide for 2025

Preparing for SQL-related interviews at Amazon? This guide provides ​60+ essential SQL questions, real-world examples, and insider insights into Amazon’s interview process. Whether you’re applying for roles like Business Intelligence Engineer (BIE), Data Analyst, or Data Scientist, mastering these concepts will give you a competitive edge.

​Amazon SQL Interview Process Overview​

Amazon’s SQL interviews typically follow a structured three-stage process:

1. ​**Initial Screening (Phone/Online Assessment)**​

   • Recruiters verify basic SQL knowledge through definitional questions. Example:
     “Explain the difference between SQL and MySQL.”
   • Candidates may receive timed coding challenges on platforms like HackerRank or Codility.

2. ​**Technical Interviews (Live Coding/Whiteboard Sessions)**​

   • ​Live Coding: Solve SQL problems in real-time using tools like SQL Fiddle. Example task:
     “Calculate month-to-month user retention rates using a timestamped user activity table.”
   • ​Whiteboard Tests: Write complex queries without execution, focusing on logic. Example:
     “Find IDs where two or more category values match in a table with columns (ID, category, value).”

3. ​Onsite/Virtual Onsite (VO) Rounds​

   • 5-6 rounds focusing on advanced SQL, system design, and leadership principles. Expect scenario-based questions like:
     “Optimize a slow-running query on a table with 50M records.”

​Top 25 Amazon SQL Interview Questions​

​Core Concepts​

1. ​Difference Between SQL and MySQL​

   • SQL: Standard language for relational databases.
   • MySQL: Open-source RDBMS that implements SQL.

2. ​Joins Explained​

   • “Describe INNER JOIN vs. LEFT JOIN in a customer/orders table scenario.”

3. ​Index Optimization​

   • When to use clustered vs. non-clustered indexes for large datasets.

​Intermediate Challenges​

4. ​Data Aggregation​

   • “Write a query to sum the QUANTITY column from a 2GB CSV file loaded into a temp table.”

5. ​Duplicate Management​

   • “Delete duplicate FName records while retaining the earliest entry by ID.”

     DELETE FROM Employee  
     WHERE Id NOT IN (  
         SELECT MIN(Id)  
         FROM Employee  
         GROUP BY FName  
     );  ```
     

6. ​Ranking & Filtering​

   • “Find the 3rd highest salary without using TOP/LIMIT.”

     SELECT MAX(Salary)  
     FROM Employee  
     WHERE Salary < (  
         SELECT MAX(Salary)  
         FROM Employee  
         WHERE Salary < (SELECT MAX(Salary) FROM Employee)  
     );  ```
     

​Advanced Scenarios​

7. ​Partitioning for Performance​

   • Horizontal partitioning strategies for tables exceeding 100M rows.

8. ​Deadlock Resolution​

   • Techniques to prevent deadlocks in high-concurrency environments.

9. ​CTE vs. Subqueries​

   • Optimize recursive queries (e.g., generating 1-100 numbers) with Common Table Expressions:

     WITH CTE AS (  
         SELECT 1 AS Number  
         UNION ALL  
         SELECT Number + 1 FROM CTE WHERE Number < 100  
     )  
     SELECT * FROM CTE;  ```
     

10. ​Backup & Recovery​

    • Design a backup strategy combining full, differential, and transaction log backups.

​Real-World Examples from Amazon Interviews​

​Case Study 1: User Retention Analysis​

Problem: “Calculate monthly retention rates for an e-commerce platform.”
Solution Framework:

1. Identify user activity per month with GROUP BY user_id, MONTH(event_date).
2. Use self-joins or window functions to track consecutive monthly logins.
3. Calculate retention as (Returning Users / Total Users) * 100.

​Case Study 2: Data Mismatch Resolution​

Problem: “Join two tables (1M and 100 records) where a LEFT JOIN returns unexpected NULLs.”
Debugging Steps:

1. Verify JOIN conditions and aliases.
2. Check for data type mismatches (e.g., VARCHAR vs. INT).
3. Analyze execution plans for index usage.

​Preparation Tips for Success​

• ​Practice Platforms: Use LeetCode, StrataScratch, and Amazon Redshift sandboxes.
• ​Behavioral Alignment: Link SQL solutions to Amazon Leadership Principles (e.g., “How did your query optimization reflect Customer Obsession?”).
• ​Performance Tuning: Master indexing, query hints, and execution plan analysis.

​Amazon SQL Interview Questions: Key Takeaways​

From foundational syntax to large-scale optimization, Amazon’s SQL interviews test both technical depth and practical problem-solving. Use this guide to refine your skills, and remember: practice with real datasets and mock interviews is critical.

Optimize your preparation today, and you’ll be ready to tackle even the most complex SQL challenges at Amazon!