ciao,
sto provando la soluzione ajax: questo è il codice della finestra principale con il form

codice:
<?php include("../connection.php"); ?>

<?php

//query for the filter form (tabel  resource)
$query = "SELECT name FROM resource";


//execute query
$result = mysql_query($query, $con);
if (!$result) {
    die('Invalid query: ' . mysql_error());
}

?>

<html>
    <head>
        <title>User Editor (EACS)</title>
		<link rel=stylesheet href="../style.css" type="text/css">
		<script type="text/javascript"> 

			var http = createRequestObject(); 
			var where = (navigator.appName == "Microsoft Internet Explorer") ? -1 : null; 

			function createRequestObject() { 
				var ro; 
				var browser = navigator.appName; 
				if(browser == "Microsoft Internet Explorer"){ 
					ro = new ActiveXObject("Microsoft.XMLHTTP"); 
				}else{ 
					ro = new XMLHttpRequest(); 
				} 
			return ro; 
			}

			function addElement(ogg,val,text){ 
				var newOption; 
				newOption = document.createElement("option"); 
				newOption.value = val; 
				newOption.text = text; 
				ogg.add(newOption, where);     
			} 

			function removeElement(ogg){ 
				if(ogg.options.length > 0){ 
					while (ogg.options.length) { 
						ogg.remove(0); 
					}	     
				} 
			} 

			function disabledElement(ogg,val){ 
				document.getElementById(ogg).disabled = val; 
			} 

			function loadingAttributes(oggId){ 
				var res = document.getElementById(oggId).value; 
				//alert('getAttributes.php?res=' + res);
				http.open('GET','getAttributes.php?res=' + res, true); 
				http.onreadystatechange = getAttributes; 
				http.send(null);   
			} 

			function getAttributes(){ 
				var Attribute = document.getElementById('filter2'); 
				removeElement(Attribute); 
				id = document.getElementById('filter1').value; 
				if(id == 'filter1'){ 
					disabledElement('filter2',true); 
					addElement(Attribute,'sel','Select a resource before:'); 
				}else{ 
					if(http.readyAttribute == 4){ 
						if (http.status == 200) { 
							var response = http.responseText; 
							if(response == ''){ 
								disabledElement('filter2',true); 
								addElement(Attribute,'sel','No Attributes'); 
							}else{ 
								removeElement(Attribute); 
								coppia = response.split(','); 
								max = coppia.length; 
								addElement(Attribute,'sel','Select a resource:'); 
								for(x=0;x<max;x++){ 
									val = coppia[x]; 
									addElement(Attribute,val,val); 
								}	 
								disabledElement('filter2',false); 
							} 
						} 
					}else{ 
						addElement(Attribute,'sel','Loading...'); 
					} 
				} 
			} 
</script>
    <body>
		<div id="form">
			<form id="form1" name="form1" method="post" action="">
				<select name="filter1" id="filter1" onchange="loadingAttributes('filter1');">
					<option value="">---</option>
					<?php while ($row = mysql_fetch_assoc($result)) {?> 
						<option value="<?php echo $row['name'];?>"><?php echo $row['name'];?></option>
					<?php } ?>
				</select>
				.
				<select name="filter2" id="filter2">
					<option value="">---</option>
				</select>
			</form>
		</div>
    </body>
</html>
Mentre la pagina php che interroga il db e mi ritorna gli attributi e la seguente:
Codice PHP:

getAttributes.php

<? include("../connection.php");


//load resource name
$resource = $_REQUEST['res']; 
  
  
  
//query for the filter form (tabel  resource)
$query = "SELECT attributes FROM resource WHERE name ='$resource'";


//execute query
$result = mysql_query($query, $con);
if (!$result) {
    die('Invalid query: ' . mysql_error());
}

$attributes="";

while ($row = mysql_fetch_assoc($result)) {
    $attributes = $row['attributes'];
}

echo $attributes;  

?>
Il problema è che http.readyAttribute mi ritorna "undefined", cosa può essere?