title: How to sort a binding source with joins?
body: <p>I have a table called Tenants, and it has a field called PropertyID and UnitID.</p>
  
  <p>I also have a binding source for this table (Tenants), however I want it sort it, but the values I want to sort it by are not in the table itself.</p>
  
  <p>I want to do something like this:</p>
  
  <pre><code>SELECT t.*, p.PropertyName, u.UnitNumber FROM Tenants t
  LEFT JOIN Properties p ON t.PropertyID = p.ID
  LEFT JOIN Units u ON t.UnitID = u.ID
  ORDER BY p.PropertyName, u.UnitNumber
  </code></pre>
  
  <p>How can I do this with the binding source?</p>