Codeigniter中的Stdclass对象数组？

Question

我得到如下所述的输出我需要将这些std类对象转换为数组

输出值

stdClass Object
(
    [PRODUCT_CODE] => PRD000001
)
stdClass Object
(
    [PRODUCT_CODE] => PRD000003
)

所需输出

$data = array('PRD000001','PRD000003');

我使用下面的代码如何实现所需的格式

$this->db->select('PRODUCT_CODE');
$this->db->from('NT_PATIENT_MEDICINE_LOG');
$this->db->where_in('PATIENT_CODE',$patient_code);
$query = $this->db->get();

if ($query->num_rows() >= 1) {
    $result = $query->result_array();
    foreach($result as $key => $value):
        $data = array();           

        $data[] = $value[$key]['PRODUCT_CODE'];
        echo "<pre>";print_r($data); 
    endforeach;
}