Sql quiz

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

In `WHERE name LIKE 'A%'`, what does `%` mean?

1. In `WHERE name LIKE 'A%'`, what does `%` mean?
2. Which keyword sorts the result set?
3. Which is the correct way to test "this column has no value"?
4. How do you limit a result to the first 10 rows in standard SQL (and PostgreSQL/MySQL/SQLite)?
5. What does `INSERT INTO users (email) VALUES ('a@b')` do?
6. ``` SELECT u.name, o.id FROM users u JOIN orders o ON o.user_id = u.id; ``` Which type of join is this (implicit / explicit)?
7. Which expression returns a value depending on a condition row-by-row?
8. ``` SELECT department, AVG(salary) FROM employees GROUP BY department; ``` What does this query return?
9. ``` 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?
10. What does a `UNIQUE` constraint provide that `PRIMARY KEY` does not (and vice versa)?
11. What does SQL stand for, and what is it primarily used for?
12. What is the difference between `COUNT(*)` and `COUNT(col)`?

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