Database
Database related cheatsheet collection - 4 quick reference guides. Find fast, copy directly. The essential online command reference for developers and SRE.
MySQL Cheatsheet - MySQL Command Reference
A MySQL command handbook for DBAs, backends, and data analysts, covering database & table management, CRUD, index optimization and slow-query localization with EXPLAIN, user privileges, logical backup & recovery, and replication — highlighting operations that can lock tables or stall replication.
PostgreSQL Cheatsheet - PostgreSQL Command Reference
A PostgreSQL command handbook for backend engineers, DBAs, and data analysts, covering connection & role management, database & table operations, EXPLAIN analysis, lock & transaction troubleshooting, pg_dump/pg_restore backup & recovery, and streaming replication, with paths for locating lock waits and table bloat.
MongoDB Cheatsheet - MongoDB Command Reference
A MongoDB reference for backend engineers, covering database & collection management, document CRUD, query operators, index strategies that keep queries off full collection scans, the aggregation pipeline, and replica-set vs sharded-cluster responsibilities.
SQL JOIN Cheatsheet - SQL JOIN Query Reference
A SQL JOIN reference for writing multi-table queries correctly, covering INNER, LEFT/RIGHT/FULL OUTER, CROSS, self-joins, USING/natural joins, and when a correlated subquery with EXISTS beats a JOIN — plus the row-duplication pitfall of joins on one-to-many tables.