title: Referencing one column of a composite primary key as a foreign key
body: <p>In the <code>table A</code>, I've got a composite of 3 fields as a <code>primary key</code> and in the <code>table B</code> I've got one of the composite (which is not unique). I'd like to reference with the <code>table A</code> to ease the <code>delete</code> (with <code>ON DELETE CASCADE</code>).</p>
  
  <p>So, am I compelled to put the other two fields in the table B and reference with this <code>composite</code> or is there another solution?</p>