title: Doctrine Query Builder CONCAT in GROUP BY
body: <p>I would like to add CONCAT in ORDERBY function in doctrine 2. </p>
  
  <p>Tried searching in doctrine docs and browsed in web but unable to find a solution for this  </p>
  
  <p>Below syntax is throwing an error </p>
  
  <pre><code> $qb = $this-&gt;createQueryBuilder("t");
   $qb-&gt;addOrderBy('CONCAT(tep.echtgenootNaam,tep.eigennaam)', $direction);
  </code></pre>