The ideal scenario for Hibernate is to start with a domain model and let the framework generate a database schema for you. In those infrequent times you get to do greenfield development, you may even be able to take advantage of that capability. Normally, however, when writing a new application you are given an existing database and told not to modify it. For these situations, GORM provides an excellent custom ORM mapping mechanism. This talk will demonstrate the process of mapping to an existing database, with one-to-many and many-to-many associations, stored procedures, functions, and more.