A popular SQL Database, recently made open source.

MySQL is something of a cross between a normal Relational Database and a simple filesystem. It's missing a number of features, such as triggers, subselects, and foreign keys, but it's about as fast as you can get for pure read speed.

(Now transactions are also supported, but if you read the documentation, you'll discover roads more clever than transactions that bring you to the same results)

(Also, triggers, subselects, and foreign keys, are now supported in version 5.0)

A commonly used tool for MySQL is phpMyAdmin, a php driven front-end.

MySQL web page:

http://www.mysql.com

phpMyAdmin:

http://phpmyadmin.sourceforge.net

In effetti è un OttimoDatabase