How to use 'interval' in Doctrine2 Query Builder

@Kiran write only about DATE_ADD, but you can also use DATE_SUB

$qb->andWhere("DATE(a2_.updatedAt) = DATE_SUB(CURRENT_DATE(), 6, 'day')");

It is equivalent of SQL:

DATE(a2_.updatedAt) = DATE_SUB(CURRENT_DATE, INTERVAL 6 DAY)

As far as I know, Interval is not ported in Doctrine. The workaround I found is to work directly on the DateTime I pass as a param (here, I'd like to use interval of 2 days, passed through Datetime):

public function findOngoingPublicEvents()
{
    return $this->createQueryBuilder('e')
        ->where('e.isActive = 1')
        ->andWhere('e.isPublic = 1')
        ->andWhere('e.begin <= :begin')
        ->andWhere('e.end >= :end')
        ->orderBy('e.id', 'ASC')
        ->setParameter('begin', new \DateTime('+2 days'))
        ->setParameter('end', new \DateTime('-2 days'))
        ->getQuery()
        ->execute();
}

If you want to use INTERVAL (in Doctrine 2, DQL) on mysql comumn field, You can use as below,

$qb->andWhere("DATE_ADD(pv.myDAte,48,'hour') >= UTC_TIMESTAMP()");

It will print SQL as below,

...... DATE_ADD(p0_.appointment_date, INTERVAL 48 HOUR) >= UTC_TIMESTAMP() .....