[flexcoders] How to populate a ComboBox?

[xaero]

I'm working with flex and amfphp (under Adobe 's php_ria_sdk  that
downloaded from:
http://www.adobe.com/devnet/flex/articles/flex_php_sdk.html)

I'v got a problem with ComboBox....I donn't how to populate the data
that read from the database.
The table of the database is like this:
-----------------------------
sid  |  atclass   |  ssname
-----------------------------
1      |        1         |  Joe
2      |        1         |  Jack
3      |        1         |  Bob
4      |        3        |  Sam
5      |        3         |  Halen
-----------------------------
I use this function in my .php file to read the data:

function getStudents($atClass) {
         # Return a list of all the users
         $sql = "SELECT * from students where atclass = '".$atClass."'";
         if ([EMAIL PROTECTED]>mysqli->query($sql)) {
             $errno=$this->mysqli->errno;
             $this->mysqli->close();
             trigger_error("AMFPHP Remoting  class database SELECT query
error: " . $errno);
         }
         while ($row = $result->fetch_assoc()) {
             $user_array[] = $row;
         }
         return($user_array);
     }

How can I populate the ComboBox with the data in $user_array ?
The `ssname` field  --------  ComboBox's label.
And the `atclass` field -------------- ComboBox's data.