title: Order by one column and then by another column
body: <p>I have an <a href="http://sqlfiddle.com/#!6/0d5fc/6" rel="nofollow noreferrer">SQL Fiddle</a> and the table looks like below</p>
  
  <pre><code>TicketId    EmployeeId  BookingRef  DepartureDate   DepartureTime      
  1           1110341     8662225387  2017-10-16      14:00:00.0000000    
  2           1110341     8662225388  2017-10-17      14:36:00.0000000    
  3           1110341     8662225388  2017-10-17      21:39:00.0000000    
  4           1110341     8662225389  2017-10-12      17:15:00.0000000    
  5           1110341     8662225390  2017-10-12      18:42:00.0000000    
  6           1110341     8662225390  2017-10-16      14:15:00.0000000    
  </code></pre>
  
  <p>I want to order it by DepartureDate, DepartureTime and BookingRef however related BookingRef should be partitioned together So the above result should look like</p>
  
  <pre><code>TicketId    EmployeeId  BookingRef  DepartureDate   DepartureTime      
  4           1110341     8662225389  2017-10-12      17:15:00.0000000    
  5           1110341     8662225390  2017-10-12      18:42:00.0000000    
  6           1110341     8662225390  2017-10-16      14:15:00.0000000    
  1           1110341     8662225387  2017-10-16      14:00:00.0000000
  2           1110341     8662225388  2017-10-17      14:36:00.0000000    
  3           1110341     8662225388  2017-10-17      21:39:00.0000000
  </code></pre>