title: Explain this SQL query in plain English
body: <p>Please explain, in plain English, what question this SQL query answers:</p>
  
  <pre><code>SELECT SUM(price) FROM Room r, Hotel h
  
  WHERE r.hotelNo = h.hotelNo and hotelName = 'Paris Hilton' and
  roomNo NOT IN
  
  (SELECT roomNo FROM Booking b, Hotel h
  WHERE (dateFrom &lt;= CURRENT_DATE AND
  dateTo &gt;= CURRENT_DATE) AND
  b.hotelNo = h.hotelNo AND hotelName = 'Paris Hilton');
  </code></pre>