使用连接表获取选择，while循环需要一个数组，否则不会获取任何内容

I have a method below, that selects some comments. I'm having issues getting the data, not because the query doesn't work but the while loop doesn't fetch the data if I don't use an array, here is my code

public function selectAllComment($idarticle) { $db = $this->getBdd();

    $sql = $db->query('SELECT c.comment, c.date_comment 
                                      FROM comments as c 
                                      INNER JOIN joint_a_comments on joint_a_comments.id_comment = c.id
                                      INNER JOIN articles a ON joint_a_comments.id_article = a.id
                                      WHERE a.id ="'.$idarticle.'"
                                      ORDER BY c.date_comment DESC 
                                      LIMIT 0,10');

    while($result[] = $sql->fetch(PDO::FETCH_ASSOC))
    {
        $rescomment[] = new Comments($result);
    }

    return $rescomment;

With this above, I can see that the data are fetched using var_dump on $result. However, first problem is: 1- if I do the same with the object i.e. $rescomment (I instantiate a class to hydrate the data and I use them in a view...). 2- If I remove the brackets [] from $result, I get "boolean false"....any idea guys?