Doctrine is an object relational mapper (ORM) for PHP 5.2.3+ that 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.
Doctrine offers a database import feature which will generate your php models or yaml schema files from an existing database.
Doctrine offers the ability for you to write raw SQL statements and let Doctrine map the result into objects (or arrays, or a scalar result set). Apart from that you can always use plain SQL as you would do it without Doctrine.