multi combo

<html>
<head>

<script language="JavaScript" type="text/JavaScript">

 function showstream()
 {
 <?php

 // membaca semua stream
 $query = "SELECT * FROM STREAM";
 $hasil = mysql_query($query);

 // membuat if untuk masing-masing pilihan stream beserta isi option untuk combobox kedua
 while ($data = mysql_fetch_array($hasil))
 {
   $stream = $data['STREAM'];

   // membuat IF untuk masing-masing stream
   echo "if (document.pkl_telkom.materi_training.value == \"".$stream."\")";
   echo "{";

   // membuat option materi untuk masing-masing stream
   $query2 = "SELECT * FROM materi_training WHERE STREAM = $stream";
   $hasil2 = mysql_query($query2);
   $content = "document.getElementById('M_TRAINING').innerHTML = \"";
   while ($data2 = mysql_fetch_array($hasil2))
   {
       $content .= "<option value='".$data2['Kode_M']."'>".$data2['NAMA_M_TRAINING']."</option>";
   }
   $content .= "\"";
   echo $content;
   echo "}\n";
 }

 ?>
 }
</script>

</head>
<body>
<h1>Demo</h1>
<form name="demo"  method="post"  action="submit.php">
<table>
<tr><td>Pilih Stream</td><td>:</td>
      <td>
          <select name="stream" onchange="showstream()">
          <option>Silakan Pilih</option>
          <option>------------------------</option>
          <?php
                 // query untuk menampilkan propinsi
                 $query = "SELECT * FROM STREAM";
                 $hasil = mysql_query($query);
                 while ($data = mysql_fetch_array($hasil))
                 {
                    echo "<option value='".$data['STREAM']."'>".$data['STREAM']."</option>";
                 }
          ?>
          </select>
      </td>
</tr>
<tr><td>Pilih Materi</td><td>:</td>
      <td>
      <select name="materi" id="M_TRAINING">
      </select>
      </td>
</tr>
</table>
</form>
</body>
</html>