title: Must a natural join be on a shared primary key?
body: <p>Suppose I perform A natural join B, where:  </p>
  
  <p>A's schema is: (aID), where (aID) is a primary key.<br>
  B's schema is: (aID,bID), where (aID, bID) is a composite primary key.  </p>
  
  <p>Would performing the natural join work in this case? Or is it necessary for A to have both aID and bID for this to work?</p>