Object-Relational-Mapper for PHP. Doctrine 2 is an object-relational mapper (ORM) for PHP that provides transparent persistence for PHP objects. It sits on top of a powerful database abstraction layer (DBAL). One of its key features is the option to write database queries in a proprietary object oriented SQL dialect called Doctrine Query Language (DQL), inspired by Hibernates HQL. This provides developers with a powerful alternative to SQL that maintains flexibility without requiring unnecessary code duplication.

The Doctrine Project provides several libraries primarily focused on database storage and object mapping.