title: SQL Sum of Sums
body: <p>I have calculated the sum of a count in different tables. This is done twice, once for each <code>performanceID</code>. Now I want to get the sum of the two sums.</p>
  
  <p>Below is the code for the two sums that I do at the moment:</p>
  
  <pre><code>    SELECT SUM((COUNT (BookingID) * CategoryPrice)) AS TotalAmount
      FROM Booking, Production
      WHERE Booking.PerformanceID IN(SELECT PerformanceID FROM Performance WHERE PerformanceID = '1')
      and Production.ProductionID IN 
      (SELECT ProductionID FROM Performance WHERE PerformanceID = '1') 
      GROUP BY BookingID, CategoryPrice
      UNION ALL
      SELECT SUM((COUNT (BookingID) * CategoryPrice)) AS TotalAmount
      FROM Booking, Production
      WHERE Booking.PerformanceID IN(SELECT PerformanceID FROM Performance WHERE PerformanceID = '2')
      and Production.ProductionID IN 
      (SELECT ProductionID FROM Performance WHERE PerformanceID = '2')
       GROUP BY BookingID, CategoryPrice
  </code></pre>
  
  <p>The results I get are:</p>
  
  <pre>
  TOTALAMOUNT
  -----------
           70
           60 
  </pre>
  
  <p>How do I sum up the two sums here?</p>