如何用两个表单实现两级分类？？求高手赐教！！！不胜感激！！！

不好意思，代码如下，请您给看看！！！多谢！！！
<form method="post" action="subscribeorder.php" name="form2" >
 <tr>
                                           
                                            <td width="24%" height="30" align="center" bgcolor="#F0F0F0" class="font_small_black" style="border-top: 1px solid #ffffff;border-right: 1px solid #ffffff;border-left: 1px solid #ffffff; ">选择一级行业 </td>
                                           
                                            <td width="76%" bgcolor="#FFFBEE" style="border-top: 1px solid #ffffff;border-right: 1px solid #ffffff ">　
                                            
                                              <select name="select1" class="font_gray333333" >
                                                  <option selected value="all">请选择行业</option>
                                                  <?php 
                                               
                                                   $subscribeorder=new subscribeorder();
                                                   $parentid=1;
                                                   $res=$subscribeorder->GetindustryList($parentid);                                                     foreach($res as $row)
                                                     {
                                                      echo '<option value='.$row["INDUSTRYID"].'>'.$row["INDUSTRYNAME"].'</option>';
                                                     }
                                                 ?>
                                                  </select></td>
                                          </tr>
                                        </form>
                                          <form method="post" action="subscribeorder.php" name="form1" >
                                           <tr>
                                            <td width="24%" height="30" align="center" bgcolor="#F0F0F0" class="font_small_black" style="border-top: 1px solid #ffffff;border-right: 1px solid #ffffff;border-left: 1px solid #ffffff; ">选择二级行业 </td>
                                            <td width="76%" style="border-top: 1px solid #ffffff;border-right: 1px solid #ffffff "><table width="100%" border="0" cellspacing="3" cellpadding="0">
                                                <tr bgcolor="#FFFBEE">
                                                  <td width="36%" rowspan="2"><select name="select2" size="5" multiple="multiple" class="font_gray333333" style="BORDER-RIGHT: #000000 1px solid; BORDER-TOP: #000000 1px solid; FONT-SIZE: 12px; BORDER-LEFT: #000000 1px solid; WIDTH: 150px; BORDER-BOTTOM: #000000 1px solid" ondblclick="addSrcToDestListEx(srcList, brandList);">
                                                                                <?php
                                                                    
                                                                                $industry ="$_REQUEST('form2.select1')";
                                                                                //$industry=$select1;
                                                                                $res1=$subscribeorder->Getindustrylist2($industry);
                                                                                foreach ($res1 as $row){
                                                                                echo '<option value='.$row["INDUSTRYID"].'>'.$row["INDUSTRYNAME"].'</option>';
                                                                                }
                                                                              ?>
                                                                              </select></td>
                                                  <td width="16%" height="34" align="center"><input name="button1" type="button"  value="添加&gt;"  onclick="javascript:addSrcToDestList()"/></td>
                                                  <td width="48%" rowspan="2"><select name="select" size="5" multiple="multiple" class="font_gray333333" style="BORDER-RIGHT: #000000 1px solid; BORDER-TOP: #000000 1px solid; FONT-SIZE: 12px; BORDER-LEFT: #000000 1px solid; WIDTH: 150px; BORDER-BOTTOM: #000000 1px solid" ondblclick="addSrcToDestListEx(srcList, brandList);">
                                                  </select></td>
                                                </tr>
                                                <tr>
                                                  <td align="center" bgcolor="#FFFBEE"><input name="button2" type="button" value="&lt;删除"  onclick="javascript:deleteFromDestList()"/></td>
                                                </tr>
                                                <tr bgcolor="#FFFBEE">
                                                  <td align="center" class="font_small_blue">按Ctrl可多选</td>
                                                  <td>&nbsp;</td>
                                                  <td>&nbsp;</td>
                                                </tr>
                                                <tr bgcolor="#FFFBEE">
                                                  <td colspan="3" align="center"><input name="Submitorder" type="submit" value="确认订阅" /></td>
                                                </tr>
                                            </table></td>

                                          </tr>
  </form>