我无法替换上传的pdf

Question

   //code to replace the uploaded file
   $search=mysql_query("SELECT * FROM `case`  WHERE id='$h_id'");
   $searchrow=mysql_fetch_array($search);
   $attach=$searchrow['attachment'];

   $image1= addslashes(file_get_contents($_FILES['file']['tmp_name']));
   $image_name1= addslashes($_FILES['file']['name']);
   move_uploaded_file($_FILES["file"]["tmp_name"], "../client/attachments/".$attach);
   //but that replacement is not take place.