Sql quiz

Test your Sql knowledge with a free interactive quiz — 50 questions with answers and explanations. No signup needed to play.

What does `INSERT INTO users (email) VALUES ('a@b')` do?

1. What does `INSERT INTO users (email) VALUES ('a@b')` do?
2. ``` SELECT user_id, COUNT(*) AS orders FROM orders WHERE created_at >= '2026-01-01' GROUP BY user_id HAVING COUNT(*) > 5; ``` What does this return?
3. What does `SELECT DISTINCT col FROM t` return?
4. What is the purpose of a column alias (`SELECT total AS amount`)?
5. What does a `FOREIGN KEY` constraint do?
6. What does `WHERE country IN ('UA', 'PL', 'DE')` do?
7. What does `LEFT JOIN orders o ON o.user_id = u.id` return for users with no orders?
8. ``` SELECT department, AVG(salary) FROM employees GROUP BY department; ``` What does this query return?
9. What is the practical difference between `DELETE FROM t` and `TRUNCATE TABLE t`?
10. In `WHERE name LIKE 'A%'`, what does `%` mean?
11. What does a `PRIMARY KEY` constraint guarantee?
12. What does `INNER JOIN` return?

More quizzes