title: How to compute a natural join?
body: <p>Could someone explain to me what is going on here and how to solve this problem?</p>
  
  <p>Suppose relation R(A,B) has the tuples:</p>
  
  <pre>
  A B
  1 2
  3 4
  5 6
  </pre>
  
  <p>and the relation S(B,C,D) has tuples:</p>
  
  <pre>
  B C D
  2 4 6
  4 6 8
  4 7 9
  </pre>
  
  <p>Compute the natural join of R and S. Then, identify which of the following tuples is in the
  natural join <br> R |>&lt;| S. You may assume each tuple has schema (A,B,C,D).</p>
  
  <p>I don't know what a natural join truly means. Can you explain it to me?</p>