Syntax error: row 0, column 81: error: expected literal, resulting in "NULL"

Question

I got an error [Syntax Error] line 0, col 81: Error: Expected Literal, got 'NULL'when I try to execute a request through the query builder

        $qb = $this->createQueryBuilder('r')
            ->select('r')
            ->where('r.query = :query')
            ->setParameter('query', $query)   
            ->andWhere('r.lang = NULL')
        ;

        return $qb->getQuery()->getOneOrNullResult();

Field

r.lang defined as:

/**
 * @var integer
 *
 * @ORM\ManyToOne(targetEntity="\BW\LocalizationBundle\Entity\Lang")
 * @ORM\JoinColumn(name="lang_id", referencedColumnName="id")
 */
private $lang;

Help solve the problem, please

Answer 1

When you check for NULL, the expression should be

->andWhere('r.lang IS NULL')