update ทีละหลาย record บันทึกครบบ้าง ไม่บันทึกครบบ้าง ทำไงดีครับ

$co = count($arr_p);
for ($j=0;$j<$co;$j++){
          mysql_query("set NAMES utf8 ");
         mysql_query("SET character_set_results=utf8");
         mysql_query("SET character_set_client=utf8");
         mysql_query("SET character_set_connection=utf8");

        $strSQL = "update sum_chk_in".$mix_year_term." set kat ='$arr_k[$j]', nee = '$arr_r[$j]',la = '$arr_l[$j]',ma='$arr_m[$j]',percent ='$arr_p[$j]',comment = '$arr_c[$j]' where ( year_m='$year_m')and (term_m='$term_m')and(tea_code='$tea_code') and(subject_code='$subject_code')and (class_code='$class_code')and(room_code='$room_code') and(std_code='$arr_id[$j]')";
          mysql_query("set NAMES utf8 ");
          mysql_query($strSQL);

}