title: Avg of a Sum in one query
body: <p>I would like to know if I can get the average of a sum in one single SQL SERVER request,</p>
  
  <p>Have tried to do it with the following request but it doesn't work:</p>
  
  <pre><code>  SELECT t.client, 
           AVG(SUM(t.asset)) AS Expr1
      FROM TABLE t
  GROUP BY t.client
  </code></pre>