title: How does JPA orphanRemoval=true differ from the ON DELETE CASCADE DML clause
body: <p>I am a little confused about the JPA 2.0 <code>orphanRemoval</code> attribute.</p>
  
  <p>I think I can see it is needed when I use my JPA provider's DB generation tools to create the underlying database DDL to have an <code>ON DELETE CASCADE</code> on the particular relation.</p>
  
  <p>However, if the DB exists and it already has an <code>ON DELETE CASCADE</code> on the relation, is this not enough to cascade the deletion appropriately? What does the <code>orphanRemoval</code> do in addition?</p>
  
  <p>Cheers</p>