php - 非オブジェクトのクラスクエリ PDO プロパティ

Question

私は確実にオブジェクトを持っているので、私は自分のエラーを理解していません. 以下の私のprint_rを見てください:

注意: 21 行目で C:\xampp\htdocs\travel_mvc\cockpit\index.php の非オブジェクトのプロパティを取得しようとしています

そして21行目と持っています：

echo $row->tz_name.'<br>';

私のprint_r：

Array
(
    [0] => stdClass Object
        (
            [tz_name] => Africa/Abidjan
        )

    [1] => stdClass Object
        (
            [tz_name] => Africa/Accra
        )

    [2] => stdClass Object
        (
            [tz_name] => Africa/Addis_Ababa
        )

    [3] => stdClass Object
        (
            [tz_name] => Africa/Algiers
        )

    [4] => stdClass Object
        (
            [tz_name] => Africa/Asmara
        )

)

私のクラスでは：

class model{
    private $fields = '*';
    private $table = '';
    private $where = '';
    private $and = '';
    private $limit = '';
    private $order = '';
    private $type_order = 'DESC';
    private $d = array();

    public function find($data = array()){
        if(isset($data['fields'])){
            $this->fields = $data['fields'];
        }
        $this->table = $data['table'];
        if(isset($data['where'])){
            $this->where = ' WHERE '.$data['where'];
        }
        if(isset($data['and'])){
            $this->and = ' WHERE '.$data['and'];
        }
        if(isset($data['limit'])){
            $this->limit = ' LIMIT '.$data['limit'];
        }
        if(isset($data['order'])){
            $this->order = ' ORDER BY '.$data['order'].$type_order;
        }
        $query = Db::getInstance()->prepare('SELECT '.$this->fields.' 
                                             FROM '.$this->table.$this->where.
                                             $this->and.$this->order.$this->limit.'');
        $query->execute();
        while($data = $query->fetchAll(PDO::FETCH_OBJ)){
            $d[] = $data;
        }
        return($d);
    }
}

そして、関数を呼び出すと:

$model = new model();
$sql = $model->find(array(
    'fields'=>'tz_name',
    'table'=>'times_zones',
    'limit'=>5
));
foreach($sql as $row):
    echo $row->tz_name.'<br>';
endforeach;
echo '<pre>';
print_r($row);
echo '</pre>';