Doctrine: Object Relational Mapping for Your PHP Development, Page 3

For Further Reading

"Doctrine ORM for PHP" (The main source of documentation for the project)

Object Relational Mapper Documentation for Doctrine

Outlet -- an open source object-to-relational mapping tool for PHP

PHP ActiveRecord -- an open source ORM library based on the ActiveRecord pattern

phpDataMapper -- an implementation of the Data Mapper pattern written in PHP5

Repose PHP ORM -- an ORM library for PHP5 that implements a Unit of Work

dORM -- a PHP 5 ORM library that requires a small XML file to map classes to their respective database tables.