SQL Advanced Core Knowledge Deep Knowledge : Use with technology: for comprehensive documentation. Common Table Expressions (CTEs) Basic CTE Multiple CTEs Recursive CTEs Materialized CTE (PostgreSQL 12+) Window Functions Deep Dive Partitioned Calculations Running Calculations Gap and Island Analysis First/Last in Group Query Optimization EXPLAIN Basics Reading EXPLAIN Output | Term | Meaning | |------|---------| | | Full table scan (often bad) | | | Using index (good) | | | Using covering index (best) | | | Using multiple indexes | | | Estimated startup..total cost | | | Estimated rows return…