named query

named query is a great tool provided by jpa while developing your dao classes.. (i mean it is used while developing dao classes, not tool for doing the job itself..)

http://blogs.sun.com/JPQL01/entry/named_query_in_java_persistence

here is some sample use cases: http://www.java2s.com/Code/Java/JPA/Named-Query.htm

here is a jpql tutor: http://www.jpox.org/docs/1_2/jpa/named_query.html