bulan_tagihan.php

<?php
$host   = "localhost"; //Ganti dengan nama host anda
$user = "surdayso_user";    // Ganti dengan user phpmyadmin / database anda
$pass = "Surday19"; // Ganti dengan password database anda
$db   = "surdayso_billingv2_agus";  // Ganti dengan nama database anda
mysql_connect($host,$user,$pass) or die (mysql_error());
mysql_select_db($db) or die (mysql_error());

$id = $_POST['id'];

$query = mysql_query("SELECT bulan_tagihan FROM t_tagihan WHERE id_pelanggan = '$id' ") or die(mysql_error());
while($hasil =  mysql_fetch_array($query)){
  echo "<option value=".$hasil['bulan_tagihan'].">".$hasil['bulan_tagihan']."</option>";
}
?>