yii中使用ar可以进展嵌套吗

$c             = new CDbCriteria();
$c->join   = "left join (select goods_id, group_concat(name) as `tags` from goods_tag group by goods_id) `tag` on tag.goods_id=t.id";
$res = Goods::model()->with( 'brand' )->findAll( $c );