->join('user', 'gallery.id_user = user.id', array(
'username' => new \Zend\Db\Sql\Expression("user.firstname || ' ' || user.lastname")
))
->join('user', 'gallery.id_user = user.id', array(
'username' => new \Zend\Db\Sql\Expression("user.firstname || ' ' || user.lastname")
))