title: UNION vs DISTINCT in performance
body: <p>In SQL 2008, I have a query like so:</p>
  
  <pre><code>QUERY A
  UNION 
  QUERY B
  UNION 
  QUERY C
  </code></pre>
  
  <p>Will it be slower/faster than putting the result of all 3 queries in say, a temporary table and then <code>SELECT</code>ing them with <code>DISTINCT</code>?</p>