Doctrine query builder ~ datetime
m.postdate is a field name and therefore shouldn't be passed in as a parameter. Try this
$qb = $em->createQueryBuilder();$qb->select('m') ->from('ChatboxBundle:ChatMessage', 'm') ->where('m.postdate > :last') ->setParameter('last', new \DateTime('-5 second'), \Doctrine\DBAL\Types\Type::DATETIME);$updatedata = $qb->getQuery()->getResult();