title: JPA query for getting the whole tree
body: <p>I have a class which models all categories and they can be ordered hierarchically.</p>
  
  <pre><code>@Entity
  @Table(name="categories")
  public class Category {
      @Id
      @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="sequence")
      @SequenceGenerator(name="sequence", sequenceName="categories_pk_seq", allocationSize=1)
      @Column(name="id")
      private Long id;
  
      @Column
      private String name;
  
      @OneToOne
      @JoinColumn(name="idfather")
      private Category father;
  
  }
  </code></pre>
  
  <p>I need to get all categories ordered hierarchically (I mean every father followed by its children and fathers ordered alphabetically on each level) as they could be made for example with PRIOR in oracle. Is it possible to do this with a JPA Query (not a SQL one)?</p>
  
  <p>Thanks.</p>