อยากได้โค๊ด drop down 2 ชั้น ในตารางเดียวกัน มีรูปตัวอย่าง ค่ะ

SELECT DISTINCT(item) FROM ........

SELECT name FROM ........ WHERE item = '$dropdown1'

<script language="JavaScript">
function dropdownlist(listindex)
{
document.form1.subcategory.options.length = 0;   ///Edit Form Name
switch (listindex)
{
<?
$conn=odbc_connect("Driver={Client Access ODBC Driver (32-bit)};System=10.11.10.58;Uid=sp;Pwd=sp;","sp","sp"); 
?>
<?
$sql_="SELECT * FROM KM.Data ";
$re_= odbc_exec($conn, $sql_) or die ("Error Execute [".$sql_."]");
while ($data_= odbc_fetch_array($re_)){
 ?>
case "<?=$data_[Item]?>" :
<? 
$sql_1= "SELECT * FROM KM.Data where Item = '$data_[Item]' ";
$re_1= odbc_exec($conn, $sql_1) or die ("Error Execute [".$sql_1."]");
$i=0;
while ($data_1= odbc_fetch_array($re_1)){   ///Edit Form Name
?>
document.form1.subcategory.options[<?=$i?>]=new Option("<?=$data_1[Name];?>","<?=$data_1[Name]?>"); 
<? $i++;
}?>
break;
<? }?>
}
return true;
}
</script>

<? 
$sql="SELECT DISTINCT(Item) FROM KM.Data WHERE idItem = '11000' ";
$re=odbc_exec($conn, $sql) or die ("Error Execute [".$sql."]");
?>

</td>
</tr>
  <tr class="cssContent">
  <td align="left" width="635">
    </td>
  </tr>
    <tr>
      <td width="635" align="center" valign="top"></td>
      <td width="21" align="left" valign="top">&nbsp;</td>
      <td width="769" align="left" valign="top">
        <div class="text" style="margin:15px 0 0 10px;"><strong>รหัส :</strong></div>
        <div class="text" style="margin:10px 0 0 10px;">
  <select name="category" id="category" onchange="javascript: dropdownlist(this.options[this.selectedIndex].value);">
  <option value="">-- Select --</option>
  <? while ($data=odbc_fetch_array($re)){?>
  <option value="<?=$data[Name]?>"><?=$data[Name]?></option>
  <? }?>
  </select>
          </div>
        <div class="text" style="margin:15px 0 0 10px;"><strong>ชื่อ :</strong></div>
        <div class="text" style="margin:10px 0 0 10px;">
  <script type="text/javascript" language="JavaScript">
document.write('<select name="subcategory" id="subcategory"><option value="">-- Select  --</option></select>')
</script>
  <noscript>
  <select name="subcategory" id="subcategory" >
  <option value="">-- Select  --</option>
  </select>
  </noscript>
          </div>

<?
    odbc_close($conn);
?>