Mastery

SQL · Expert - architecture, internals and edge cases

• EXPLAIN and query plans: read what the database actually doesDecode the plan that the SQLite planner really chooses for your queries with EXPLAIN QUERY PLAN.
• Advanced indexes: composite, covering, ignored indexMaster the leftmost-prefix rule, covering indexes, and the pitfalls that make an index invisible to the planner.
• Recursive queries (WITH RECURSIVE): hierarchies and graphsTraverse trees and graphs with WITH RECURSIVE, mastering depth and cycle detection.
• Concurrency: locks, isolation levels, phantom readsUnderstand SQLite's locking model, its transactions, and the isolation anomalies described by the SQL standard.
• Security: SQL injection, privileges, prepared statementsReproduce an SQL injection, neutralize it with prepared statements, and apply least privilege.