Master SQL for data science interviews with problems covering JOINs, window functions, CTEs, subqueries, aggregations, and more. Every problem includes a built-in SQL Visualizer that shows how your query executes step-by-step — see how JOIN conditions match rows, how GROUP BY collapses data, and where your logic goes wrong. All problems run against real company-style datasets from domains like fintech, e-commerce, healthcare, and adtech, graded instantly in your browser.
816 SQL problems across 15 datasets