Articles and interactive posts. Start with the Learn MySQL series.
Pick data types, nullability, and schema choices that keep web apps correct under real traffic.
In InnoDB the primary key is the clustered index. Learn clustered lookups, secondary index bounce, and why random UUID primary keys hurt.
Build B-tree secondary indexes. Use composite leftmost prefix rules and measure selectivity without guesswork.
Write sargable WHERE clauses and tight projections so list and detail endpoints use indexes.