Databases

Firebird 2 Cheat Sheet
Lorenzo Alberton
single-page A4 reference to Firebird database, covering data types, functions, etc.

MySQL Cheat Sheet
Dave Child
single page, A4 cheat sheet covering functions and data types

PostgreSQL Cheat Sheet
Lorenzo Alberton
single-page A4 reference to PostgreSQL data types, functions, etc.

SQL Server Cheat Sheet
Dave Child
Single page reference to Microsoft's database server