Frequently asked questions

SchemaLab is a place to build practical data skills. Work through SQL problems, learn concepts in Guides, practice data-modeling decisions, and use structured feedback to understand your results.

Data analysts, analytics engineers, data engineers, and anyone building stronger SQL and data-modeling judgment, from first principles through interview preparation.

SchemaLab connects query practice with the concepts and modeling decisions behind the answer. SQL problems test what your query does; Guides explain the ideas; data-modeling practice tests how you structure a system.

Choose SQL or data modeling, open a problem, and work in its dedicated workspace. Run as often as you need, then submit when you want a verdict. Guides are available when you want to study a concept separately.

Run a timed mock interview: an AI interviewer takes you through a company-style round, you design against the prompt and field follow-ups, and you get a scored verdict across the dimensions a real interviewer weighs, clarification, grain discipline, metric fit, historical judgment, trade-off communication, and operational awareness.

A trusted grader evaluates the behavior each problem asks for and returns the result shown in the workspace. Coaching and explanations are separate from that verdict, so they do not silently change whether a submission passes.

AI feedback is optional coaching and can be imperfect. Use it to explore trade-offs or ask questions, but rely on the problem verdict and your own review of the work when deciding what is correct.

Your workspace saves automatically as you edit, so you can leave and come back to it. Your challenge attempts and completions are kept on your account so you can see what you have practiced.

No. Company-themed tracks labeled "<company>-style" are reconstructions of publicly documented interview formats, for practice realism. They are not official questions and are not affiliated with any named company.

There is a free tier for trying the practice loop, with paid plans for unlimited AI design reviews, the in-workspace tutor, and full mock interviews. You can cancel anytime; access continues until the end of the billing period.

Reset your password from the sign-in page using the "Forgot password" link. You can manage or cancel a subscription anytime from your account billing settings, when you cancel, access continues until the end of the current billing period.

We collect the minimum needed to run the product and do not sell your personal information. You can start account deletion from account settings. See the Privacy Policy for what we collect, how service providers process it, and what limited records may be retained.