title: Cartesian Product from INNER JOIN
body: <pre><code>SELECT A.x, A.y, B.m, B.n, C.p 
  FROM A,B,C 
  WHERE A.x = B.l 
    AND A.y = B.m 
    AND B.n = C.q
  </code></pre>
  
  <p>or</p>
  
  <pre><code>SELECT A.x, A.y, B.m, B.n, C.p 
  FROM A 
   INNER JOIN B ON A.x = B.l AND A.y = B.m 
   INNER JOIN C ON B.n = C.q
  </code></pre>
  
  <p>gives Cartesian product. Where am I doing wrong?</p>