title: SQL count distinct output not as wished
body: <p>%%sql</p>
  <pre><code>SELECT 
      COUNT(DISTINCT c.email) CountRockListeners
       
  FROM
      customer c
           JOIN invoice i ON c.customer_id = i.customer_id
           JOIN invoice_line il ON i.invoice_id = il.invoice_id
           JOIN track t ON il.track_id = t.track_id
           JOIN genre g ON t.genre_Id = g.genre_Id
  WHERE g.name = 'Rock' OR g.name = 'Pop'
  </code></pre>
  <p>I have this SQL code and want to return count of Rock and Pop listeners, but it only returns the count of Rock which is 59 .Pop is 32.
  So I want it to return 59+32
  Please advise?</p>