/**
* 生成唯一订单号
*/
public function build_order_no()
{
$no = date('Ymd').substr(implode(NULL, array_map('ord', str_split(substr(uniqid(), 7, 13), 1))), 0, 8);
//检测是否存在
$db = M('Order');
$info = $db->where(array('number'=>$no))->find();
(!empty($info)) && $no = $this->build_order_no();
return $no;
} 