title: Case statement for Order By clause with Desc/Asc sort
body: <pre><code>SELECT *
  FROM
      TableName
  WHERE
  ORDER BY 
      CASE @OrderByColumn
      WHEN 1 THEN Forename
      WHEN 2 THEN Surname
      END;
  </code></pre>
  
  <p>I have a statement like above which lets me dynamically choose how to order the results of a query. However, how do I specify that I want the Forename ordered <code>DESC</code> and the Surname <code>ASC</code>?</p>