title: How to update a field in doctrine to set it null
body: <p>I want to set null to a field in doctrine and here is the sentence</p>
  
  <pre><code>$em = $this-&gt;getDoctrine()-&gt;getManager();
  $qb = $em-&gt;createQueryBuilder();
  $query = $qb-&gt;update('Model\Example', 'u')-&gt;set('u.deletedAt', ':deletedAt')
  -&gt;where("u.id IN (:ids)")-&gt;setParameter('deletedAt', null)
  -&gt;setParameter('ids', $ids)
  -&gt;getQuery();
   $query-&gt;execute();
  </code></pre>
  
  <p>i think that this code should do the job, but im getting this exception</p>
  
  <blockquote>
    <p>An exception occurred while executing 'UPDATE example SET deleted_at = ?
    WHERE (id IN (?)) AND (example.deleted_at IS NULL)' with params
    [null, "5,6"]: SQLSTATE[22P02]: Invalid text representation: 7 ERROR:
    la sintaxis de entrada no es válida para integer: «5,6»</p>
  </blockquote>
  
  <p>first of all why doctrine is adding that AND (example.deleted_at IS NULL) am i doing something wrong ?</p>