5.1. Overview of SQL Databases
- MySQL
- Runs on UNIXes and NTs.
- Very fast, especially for very small loads.
- Incredibly limited and not easily extensible.
- GPLed
- Client library used to be LGPLed, but became GPLed in version 4.x and above. (this was a controversial move).
- PotgreSQL
- Runs on UNIXes and NT.
- Flexible, but still has some limitations.
- Open-Source (BSD license)
- Firebird - supports the whole SQL 92' standard. Open-Source. Not as widely accepted as MySQL and PostgreSQL, and not as fast.
- MaxDB - another database made open-source (GPL with client library as GPL).
- Oracle - A commercial, proprietary solution that costs quite a bit, but is quite fast, and supports many features other databases don't.
- SQLite - a file-based SQL database system. Very lightweight and fast, but non-networked. Public Domain.
Others
Refer to this Freshmeat Editorial about the subject.