I am using following method in a repository class to look for certain tags in my database:
public function getItemsByTag($tag, $limit = null) { $tag = \'%\'.
From the manual, the suggested way is like below:
$qb->select(array('c')) ->where($qb->expr()->orx( $qb->expr()->eq('c.reviewed', 1), $qb->expr()->eq('c.enabled', 1), $qb->expr()->like('c.tags', '?1') )) ->orderBy('c.clicks', 'DESC'));