JOINs, subqueries, CTEs, window functions, and query optimization — write SQL that scales.
Five passes over the same idea, each from a different angle. Do them in order, or jump to whichever you need.
SQL patterns cover common query structures: self-joins, correlated subqueries, recursive CTEs, LATERAL joins, pivot/unpivot, and upsert (ON CONFLICT). Window functions (ROW_NUMBER, RANK, LAG/LEAD) enable analytics without GROUP BY. Understanding EXPLAIN plans is essential for optimization.
