for循环下的陷阱-重置数据

for ($i = 2;$i <= $highestRow;$i++) {
          $res='';
          $data = [];
          $data['number'] = $objPHPExcel->getActiveSheet()->getCell("B" . $i)->getValue().'';
          $data['title'] = $objPHPExcel->getActiveSheet()->getCell("C" . $i)->getValue().'';

          //判断数据库是否已经存在
          $res = M('Stock')->where($data)->find();

          $amount = $objPHPExcel->getActiveSheet()->getCell("D" . $i)->getValue().'';
          if($res){
            $data['amount'] = $amount;
            $id = $res['id'];
            if($res['amount']!= $data['amount']){
              if($data['number']){
                $a = M('Stock')->where("id='$id'")->data($data)->save();
              }else{}
            }else{}
          }else{
            $data['amount'] = $amount;
            if($data['number']){
            M('Stock')->add($data);
            }else{}
          }
        }