ขอความช่วยเหลือเรื่อง โค้ด DropDown 2 ชั้น หน่อยครับ

 <form id="form1" name="form1" method="post" action="">
                    <select name="menugroup" id="group_id"   onchange="document.form5.submit();" >
                      <option >======เลือก======</option>
                      <? $show =  "SELECT menugroup_id, menugroup_name FROM menu_group" ; 
				 $sql1 = mysql_query($show) ;
				 while ($put = mysql_fetch_array($sql1)){
				 ?>
                      <option value="<? echo $put['menugroup_id']; ?>" > <? echo $put['menugroup_name'];?></option>
                      <? } ?>
                    </select>
                  </span></td>
                </tr>
                <tr>
                  <td height="39"  bgcolor="#CCCCCC"><div align="center"><span class="เนื้อหา">ประเภทอาหาร</span></div></td>
                  <td height="39"  bgcolor="#CCCCCC"><? $groupID = $_GET['menugroup'];
					 if($groupID!='')
					 {
						 $group_id  = $_GET['menugroup'];
						 
					 }
						 ?>
                    <select name="menutype" size="1" >
                      <option selected="selected">==เลือก==</option>
                      <? $show1 =  "SELECT menu_type.menugroup_id, menugroup_name, menutype_id, menutype_name 
FROM menu_group, menu_type
WHERE menu_group.menugroup_id = menu_type.menugroup_id  AND  menu_type.menugroup_id ='$group_id' " ; 
				 $sql2 = mysql_query($show1) ;
				 while ($put1 = mysql_fetch_array($sql2)){
				 ?>
                      <option value="<? echo $put1['menutype_id']; ?>"> <? echo $put1['menutype_name']; ?></option>
                      <? } ?>
                    </select></td>
                </tr>
              </table>
              
              <a href="Index_add=list_menu_1.php?name=<? echo $typeing ?>">
              <input type="submit" name="button2" id="button2" value="เลือก" />
              </a>
            </form>