you have to get the choice from the url by GET method.
<?php
include "../areashoppers/includes/cs_functions.php";
$choice = $_GET['choice'];
$sql = "SELECT distinct town FROM oic_areas_full WHERE region='$choice' ORDER BY town ASC";
$st = $sc_conn->query($sql);
while ($r = $st->fetch()) {
echo "<option>" . $r['town'] . "</option>";
}
?>
3
solved Populate second select list based on first select list value [duplicate]