无限级分类,抓取某元素的所有下级id

mysql> select id,invite_qke_id from tf_qke;
+----+---------------+
| id | invite_qke_id |
+----+---------------+
|   |             |
|  |              |
|  |             |
|  |             |
|  |             |
|  |              |
|  |             |
|  |             |
+----+---------------+
 rows in set (0.00 sec)

public function ttss(){
    $id = 2;
    $res = $this->son_ids($id,1);
    dump($res);
}

public function son_ids($uid,$level,&$res_data = []){
    $qkeModel =  D('Qke');

    if ($level == 1 && !$res_data){
        $res_data[] = (string)$uid;
    }

    $sonlists = $qkeModel
                ->where(['invite_qke_id' => $uid])
                ->order('id desc')
                ->field('id,invite_qke_id')
                ->select();

    if ($sonlists)
    {
        foreach ($sonlists as $k => $v)
        {
            echo $level;
            // 这个拦截需在递归上面,放下面不行!!!!---防止最下级的下级是顶级,这样会陷入死循环!--会把服务器跑死!!!!!
            if (in_array($v['id'],$res_data)){
                continue;
            }

            $this->son_ids($v['id'],$level + 1,$res_data);

            $res_data[] = $v['id'];
        }

        return $res_data;
    }
}

<pre>

array(8) {
[0] => string(1) 2
[1] => string(2) 19
[2] => string(2) 18
[3] => string(2) 17
[4] => string(2) 16
[5] => string(2) 14
[6] => string(2) 13
[7] => string(2) 11
}
</pre>