About QueryPlan
Write SQL, check the returned rows, and inspect the work SQLite chose.
Learn from the evidence
QueryPlan is an interactive SQL lab where you write queries and check their results. First, read the task and source table. Then run a query and inspect the returned rows. In the performance course, also compare the query plan with the task's requirements before revising the query or index.
The result tells you whether the query answers the question. The plan shows how SQLite finds those rows. Learning to check both helps you recognize an index search, a broad scan, or a temporary sort.
Choose a starting point
The four free foundations lessons introduce tables, SELECT, filtering, and sorting for people who are new to SQL. Start the free foundations path.
If you already write basic SQL, the 50-exercise performance course covers query plans, indexes, joins, sorting, and grouping. Module 1 is free. The $99 lifetime offer unlocks Modules 2 to 5. Try the free first performance exercise.
For an open workspace, try the free query plan visualizer. Load an example or use your own schema and query.
What the examples can teach
The lab runs SQLite in your browser. Questions about correct rows and database work carry over to other databases, but PostgreSQL and MySQL have different planners, terminology, and costs. A SQLite plan does not establish how either database will execute your query.
Read how to use QueryPlan or contact support for help with the application or course access.