Arguably the most powerful ORM (object relational mapper) for PHP. Borrowed from the wonderful Symfony project as a great way of handling database persistence.
Event Listeners in Doctrine 2
Use Events in Doctrine 2 to handle trivial portions of your domain models.
Many-to-Many with Doctrine 2
Building and testing a many-to-many relationship. This was a bit of a rocky video, but I also include some tips for debugging your Doctrine 2 configuration.
One-to-Many with Doctrine 2
Setup One-to-Many with Doctrine 2 using PHPDoc annotations.
Unit Testing Doctrine 2 Entities
Integrate Doctrine 2 into your Zend Framework project. Drive with tests first!