How good are you at SQL, really?

Ten questions on a real database in your browser, from SELECT to JOINs and subqueries. They get harder as you go. No sign-up, and you get your level at the end.

• Write a query, press Run, and it's checked against the right answer.
• Two tries per question. Not sure? Skip it.
• Your query also runs on changed data, so typing the answer in doesn't count.