Window functions, CTEs, recursive queries and query tuning, taught as claims about rows rather than as syntax to memorise.
Most SQL is learned as a vocabulary: SELECT, JOIN, GROUP BY, ORDER BY. That vocabulary is enough to get results, and it is also enough to write queries that are quietly wrong in a way nobody notices until the numbers are on a dashboard. This course treats a query as a claim about rows. Every advanced feature is a way of making that claim more precise: a CTE names an intermediate result instead of burying it, a window function reaches across a group without destroying it, a recursive query handles a shape with no fixed depth, and an upsert states exactly which columns a write is permitted to change. The graded work is executed. The challenges run against a real SQLite database and compare the rows your query returns, so nothing here is graded on whether your SQL resembles the answer key. Several of them are built so that a plausible wrong answer passes the cases you can see and fails the ones you cannot — because that is the actual shape of the mistake this material is about.