SQL Challenge

Feed your brain. Query up. Learn SQL the way you will actually use it: one query at a time, against a real database, right on your phone. SQL Challenge is a single path of original questions. Each level hands you a small database and asks for one thing, and you answer with one SELECT. A real SQLite engine ships inside the app and runs your query on the spot — no server, no signal, no waiting. Then it runs your query again on rows you have never seen. Hard-code what was on the screen and you will hear about it. That is the whole difference between a query that looked right and a query that is right. Free to start: the opening levels are free, then unlock the full path with a single one-time purchase. No subscription, no ads, no account. WRITE REAL SQL • A keyboard built for queries: a clause row for SELECT, FROM, WHERE, JOIN, GROUP BY, ORDER BY and the aggregates, and a toggle that upper-cases keywords while leaving your table and column names exactly as typed • A schema panel above the editor: every table with its columns, their types, the row counts, and the first rows to look at • A result sheet that puts your table next to the expected one, so you can see which rows are extra, which are missing, and which column came back under the wrong name FIVE WORLDS TO QUERY • Five invented databases, none of them borrowed from a tutorial: an online shop, a school, a library system, an airline and a music service • Hidden variants of the same schema — an empty table, a tie at the top, a NULL where you assumed a number, a row with nothing to join to — decide whether you answered the question or just the screen LEARN THE RIGHT WAY • Three tiers of hints from Tuple, a cyan beaver who is smug about engineering and on your side anyway • A curated solution once you pass: the obvious query, the better one, and why the difference matters • One path, no shortcuts, easy to hard: filtering and sorting, then joins, grouping and aggregates, then subqueries and common table expressions STAY MOTIVATED • XP, player levels, daily streaks and badges • Six themes, dark and light PRIVATE BY DESIGN • Works fully offline; no account, no tracking — your progress stays on your device • No ads, ever