SQL Code Questions

💻 SQL Code Questions 🔥

Want to level up your SQL skills for interviews? Practice these must-know coding questions 👇

🔹 1. Find Duplicate Records

👉 Task: Find duplicate emails in a table

💡 Hint: `GROUP BY` + `HAVING COUNT(*) > 1`

🔹 2. Second Highest Salary

👉 Task: Get the 2nd highest salary

💡 Hint: `ORDER BY` + `LIMIT` / subquery

🔹 3. Top N Records

👉 Task: Get top 5 highest-paid employees

💡 Hint: `ORDER BY salary DESC LIMIT 5`

🔹 4. Join Tables

👉 Task: Get customer names with their orders

💡 Hint: `INNER JOIN`

🔹 5. Customers with No Orders

👉 Task: Find customers who never ordered

💡 Hint: `LEFT JOIN` + `WHERE orders.id IS NULL`

🔹 6. Count Records

👉 Task: Count total users per country

💡 Hint: `GROUP BY country`

🔹 7. Running Total

👉 Task: Calculate cumulative sales

💡 Hint: `SUM() OVER (ORDER BY date)`

🔹 8. Rank Data

👉 Task: Rank employees by salary

💡 Hint: `RANK()` / `DENSE_RANK()`

🔹 9. Latest Record

👉 Task: Get the most recent order per user

💡 Hint: `MAX(date)` + `GROUP BY`

🔹 10. Delete Duplicates

👉 Task: Remove duplicate rows

💡 Hint: Use `ROW_NUMBER()` with CTE

💡 Pro Tip:

✔ Practice daily

✔ Understand logic, not just syntax

✔ Work with real datasets

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