The entity manager API that's with EJB 3.0 is a bit more conservative (limited) compared to the full set of functionality available with Hibernate. EJB 3.0 is intended to satisfy most complex query cases, but there sure a lot of them. In EJB3, Queries can be written in native SQL syntax as sort of an out. The nice thing is, with Hibernate's EntityManager, you can access the full set of Hibernate-only functionality if you need it. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4071760#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...