在CodeIgniter-3.1.4中计算每月的行程

Question

导致此错误的原因是什么？

  

遇到PHP错误   严重性：通知
  消息：未定义的变量：ride_per_m

$query = $this->db->query("SELECT YEAR(book_date_time) AS y, 
    MONTH(book_date_time) AS m, count(id) AS count FROM `bookings` WHERE 
    status=6 
    AND YEAR(book_date_time) = YEAR(CURDATE()) GROUP BY y,m");

if($query){
    foreach($query->result() as $row)
    {
        for($i=1;$i<=12;$i++){
            if($row->m==$i)
            {
                if($row->count!=0 || $row->count!=NULL){
                    $ride_per_m[$i]=$row->count;
                }
                else{
                    $ride_per_m[$i]=0;
                }
            }
            else{
                $ride_per_m[$i]=0;
            }
        }
    }
}
$push_ride_per_m=implode(',',$ride_per_m);