title: symfony2/doctrine2 dql where field is not true
body: <p>im having troubles with checking boolean field with "is not true" clause
  im getting this error:</p>
  
  <blockquote>
    <p>("[Syntax Error] line 0, col 510: Error: Expected =, &lt;, &lt;=, &lt;>, >, >=, !=, got 'IS'")</p>
  </blockquote>
  
  <p>query is build with dql. so in code i have it added like this </p>
  
  <pre><code>$dql .= " AND p.archived IS NOT TRUE ";
  </code></pre>
  
  <p>executed query:</p>
  
  <pre><code>SELECT COUNT(p.id)
  FROM Sandbox\WebsiteBundle\Entity\Pages\OfferPage p
  INNER JOIN Kunstmaan\NodeBundle\Entity\NodeVersion nv WITH nv.refId = p.id
  INNER JOIN Kunstmaan\NodeBundle\Entity\NodeTranslation nt WITH nt.publicNodeVersion = nv.id and nt.id = nv.nodeTranslation
  INNER JOIN Kunstmaan\NodeBundle\Entity\Node n WITH n.id = nt.node WHERE n.deleted = 0
  AND n.hiddenFromNav = 0
  AND n.refEntityName = 'Sandbox\WebsiteBundle\Entity\Pages\OfferPage'
  AND nt.online = 1 AND nt.lang = :lang AND p.archived IS NOT TRUE AND p.expirationDate &gt;= :date ORDER BY p.price ASC
  </code></pre>