sysop@hub:~/tools/sql-playground$

sql-playground

SQL in an afternoon: 22 short lessons, each with a task that is checked when you run your query. The practice database is a small company with users, devices and helpdesk tickets, and it lives in this page: break it as often as you like.

ten questions to try on your own

The kind of question an admin gets asked. Try first, then open one to compare.

The engine behind this page was written for it and covers what the lessons teach: SELECT with joins, grouping, sorting, WITH and queries in brackets, window functions with OVER, plus INSERT, UPDATE and DELETE with transactions. It has no UNION and no date functions, and it is stricter than some databases about GROUP BY, on purpose. Nothing you type leaves your browser. Next: the SQL basics cheat sheet with the differences between PostgreSQL, MySQL and SQL Server, and the database is slow.