Codice PHP:
<?php
$id = $_REQUEST['id'];
if ($id) {
$regione = $_POST['regione'];
}
?>
<html>
<head><title><title></head>
<body>
<form id="select" method="post" action="<?=$_SERVER['PHP_SELF']?>?id=1">
<?php if (!$regione) { ?>
seleziona regione:
<select name="regione" size="1" onclick="document.forms[0].submit()">
<option value="0">---</option>
<option value="1">Liguria</option>
<option value="2">Abruzzo</option>
<option value="3">Sicilia</option>
</select>
<?php } else { ?>
<?php
$liguria = array('Genova', 'Savona', 'Imperia', 'La Spezia');
$abruzzo = array("L'Aquila", 'Pescara', 'Teramo', 'Chieti');
$sicilia = array('Palermo', 'Catania', 'Messina', 'Siracusa', 'Trapani', 'Enna', 'Caltanissetta', 'Ragusa');
?>
<select id="provincia" size="1">
<?php
if ($regione==1) $array=$liguria;
if ($regione==2) $array=$abruzzo;
if ($regione==3) $array=$sicilia;
for ($i=0; $i<count($i); $i++)
echo "<option value=\"$i\">".$array[$i]."</option>";
?>
</select>
<?php } ?>
</form>
</body>
</html>