title: JPA/Hibernate select element not in collection
body: <p>If I have two entity classes, <code>Group</code> and <code>Person</code>, where there is a one-to-many relationship between <code>Group</code> and <code>Person</code> (that is, a person can belong to at most one group, a group can have many persons), what jpql/hql query can I use to select all <code>Person</code>s not in <code>Group</code>s?</p>
  
  <p>Something like the reverse of <code>select p from Group g inner join g.people p</code>...</p>