no soal ato kode soal

if (isset($_POST['tambah'])) {

            $kd = $_POST['kd_soal'];
            $no = $_POST['no_soal'];
            $soal = $_POST['soal'];
            $pila = $_POST['pil_a'];
            $pilb = $_POST['pil_b'];
            $pilc = $_POST['pil_c'];
            $pild = $_POST['pil_d'];
            $key = $_POST['kunci'];
//tidak boleh sama kode atau nomor??
$sql="SELECT count(no_soal) total FROM detil_soal WHERE no_soal = '$no'";//"SELECT no_soal FROM detil_soal WHERE kd_soal = '$kd'"
            $sql = mysql_query($sql)
            $row = mysql_fetch_array($sql);

            if ($row['total']!=0) {
                echo "<script>alert('No soal sama, mohon ulangi lagi');</script>";
            }
            else{


                $tambah =mysql_query("INSERT INTO detil_soal (kd_soal, no_soal, soal, pil_a, pil_b, pil_c, pil_d, `key`) VALUES ('$kd',
                                        '$no', '$soal','$pila','$pilb','$pilc','$pild','$key')") or die(mysql_error());

                header("location:input.php");


            }


        }