*American Express Recent Interview Insights for a Data Analyst Position(0-3 Years):* SQL Questions 1. Write a query to find duplicate rows in a table. 2. Explain the difference between INNER JOIN and OUTER JOIN with examples. 3. Write a query to fetch the second-highest salary from an employee table. 4. How do you use GROUP BY and HAVING together? Provide an example. 5. Write a query to find employees earning more than their managers. 6. What is a window function in SQL? Provide examples of ROW_NUMBER and RANK. 7. Write a query to fetch the top 3 performing products based on sales. 8. Explain the difference between UNION and UNION ALL. 9. How do you use a CASE statement in SQL? Provide an example. 10. Write a query to calculate the cumulative sum of sales. 11. What is a CTE (Common Table Expression), and how is it used? 12. Write a query to identify customers who have made transactions above $5,000 multiple times. 13. Explain the difference between DELETE and TRUNCATE commands. 14. How do you optimize SQL queries for better performance? 15. Write a query to find all customers who have not made any purchases in the last 6 months. 16. How do you handle NULL values in SQL? Provide examples. 17. Write a query to transpose rows into columns. 18. Explain indexing and how it improves query performance. 19. Write a query to fetch the maximum transaction amount for each customer. 20. What is a self-join, and how is it used? Data Analysis/Scenario-Based Questions 21. How would you design a database to store credit card transaction data? 22. Write a query to identify the most profitable regions based on transaction data. 23. How would you analyze customer churn using SQL? 24. Explain the difference between OLAP and OLTP databases. 25. How would you determine the average revenue per user (ARPU) from transaction data? 26. Describe a scenario where you would use a LEFT JOIN instead of an INNER JOIN. 27. Write a query to calculate YoY (Year-over-Year) growth for a set of transactions. 28. How would you implement fraud detection using transactional data? 29. Write a query to find customers who have used more than 2 credit cards for transactions in a given month. *Behavioral and Business Questions* 30. How would you approach a business problem where you need to analyze the spending patterns of premium customers?