title: SQL query operator minus is not working
body: <pre><code>(SELECT IDOperatore FROM operatore) MINUS 
  (SELECT IDOperatore FROM commessaoperatore GROUP BY IDOperatore)  
  </code></pre>
  
  <p>This query is no working, even if I try to replace <code>MINUS</code> with <code>EXCEPT</code>. 
  The singular query <code>SELECT IDOperatore FROM operatore</code> and <code>SELECT IDOperatore FROM commessaoperatore GROUP BY IDOperatore</code> are working, but if I try to put together with <code>Minus</code> operator they don't work.</p>
  
  <blockquote>
    <p>ERROR:   #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'MINUS (SELECT IDOperatore FROM commessaoperatore GROUP BY IDOperatore)' at line 1</p>
  </blockquote>