Replaces any previously specified restrictions, if any.
$qb = $conn->createQueryBuilder()
->select('u.name')
->from('users', 'u')
->where('u.id = ?');
You can optionally programatically build and/or expressions
$qb = $conn->createQueryBuilder();
$or = $qb->expr()->orx();
$or->add($qb->expr()->eq('u.id', 1));
$or->add($qb->expr()->eq('u.id', 2));
$qb->update('users', 'u')
->set('u.password', md5('password'))
->where($or);