SQL Quest › Free SQL tools
Free SQL tools
Five tools, no signup. Two find out where your SQL stands; three work on the query in front of you, entirely in your browser.
SQL Interview Readiness TestTen questions, no signup: a Skillmap and your weakest skill.SQL Skill TestA five-minute adaptive quiz that places your SQL level.SQL Query ExplainerAny SELECT, explained clause by clause in execution order.SQL Query CheckerThe mistakes that return wrong rows, and how to fix them.SQL Query OptimizerThe patterns that make a query slow, and the faster shape.
Questions
Are these SQL tools free?
Yes, all five, with no signup. The query tools run entirely in your browser; the readiness test and the skill test need no account either.
Which tool should I start with?
If you are preparing for an interview, the readiness test: ten questions tell you which SQL skill to fix first. If you have a query in front of you, paste it into the checker, then the explainer.
Practising for an interview? Every question in the bank has its own page — SQL interview questions — and each topic has a practice set: joins, window functions, ranking functions, CTEs, advanced questions.