title: except not working when using for same table in sql
body: <p>Here is my query:</p>
  
  <pre><code>select u1 from p1 
  where (added_on &gt;= NOW() - INTERVAL 1 DAY)
  EXCEPT
  select u1 from p1 
  where (added_on &gt;= NOW() - INTERVAL 15 DAY) 
  AND (added_on &lt;= NOW() - INTERVAL 2 DAY)
  </code></pre>
  
  <p>I tried MINUS, not in and not exists also,they are not working except union
  Please help me with this</p>