Beginner → Expert
SQL Mastery — The Complete Interactive Course
From your first SELECT statement to window functions, query optimization and database design. Every example runs against a real SQL engine in your browser, and every challenge is graded by comparing your result set against the reference answer.
The course
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Common questions
Do I need to install a database to take this course?
No. The course runs a real SQLite engine inside your browser, seeded with a sample company database. Nothing is installed, nothing is sent anywhere, and there is nothing you can break.
Which SQL dialect does the course teach?
It teaches PostgreSQL conventions and calls out where MySQL, SQL Server, Oracle and SQLite differ, with a labelled dialect note on the lessons where it matters. The in-browser console runs SQLite.
Is the SQL course free?
Yes. All 20 modules, the graded challenges, the timed drill and the final exam are free and need no account.
Are the exercises actually graded?
Yes. Your query runs against the same live database as the reference solution and the two result sets are compared row by row, so passing means the query is genuinely correct rather than merely plausible.
Does it cover SQL interview questions?
The final module is dedicated to interview patterns — second-highest salary, top N per group, duplicate detection, anti-joins and gaps-and-islands — alongside a timed drill and a 60-question final exam. The coding track has a separate SQL section with 102 graded problems.