jqery表格的添加和合并

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script src="jquery-1.4.4.min.js" type="text/javascript"></script>
<script language="javascript">
function addRows(){
var rows=$("#table");
var vNum=$("#table tr").filter(".rows").size()+1;
//alert(vNum);
var vTr=$("#table #tr4");
//alert(vTr);
var tClone=vTr.clone(true);
//alert(tClone[0]);
tClone[0].id="tr"+vNum;
//rows.insertBefore(tClone,$("#tr5"));
tClone.appendTo(rows).insertAfter($("#tr4"));
}
function addLBrows(){
var rows=$("#table");
var vNum=$("#table tr").filter(".rows2").size()+1;
/*$("#tr3_1").removeAttr("rowspan");
$("#tr3_1").attr("rowspan",++vNum);
var addRow=document.getElementById("tr3_1").getAttribute("rowspan")
alert(addRow);
document.getElementById("tr3_1").setAttribute("rowspan",parseInt(addRow)+(vNum++)-1);*/

var vTr=$("#table #tr3_2");
var tClone=vTr.clone(true);
tClone[0].id="tr3_"+vNum-1;
tClone.appendTo(rows).insertAfter($("#tr3_2"));
$("#tr3_1").css("rowspan",++vNum); }
function addLB(){

}
function cStyle(id){
var tr2=$("#tr2_1");
tr2.style.rowspan=""+id;
}
</script>
</head><body>
<div>
  <table width="1024" border="1" id="table">
      <tr valign="top" class="rows" id="tr1">
        <td width="43" rowspan="3" align="center" valign="middle"><p>单</p>
        <p>位</p></td>
        <td width="58" rowspan="3" align="center" valign="top"><p>小</p>
        <p>计</p></td>
        <td colspan="6" align="center" valign="top">完好车</td>
        <td colspan="11" align="center" valign="top">非完好车</td>
      </tr>
      <tr >
        <td colspan="3" rowspan="2" align="center">封存车</td>
        <td width="25" rowspan="2" align="center">执勤</td>
        <td width="29" rowspan="2" align="center">待命</td>
        <td width="30" rowspan="2" align="center">日保养</td>
        <td width="27" rowspan="2" align="center">待料</td>
        <td width="28" rowspan="2" align="center">待报废</td>
        <td colspan="3" align="center">再修</td>
        <td colspan="3" align="center">待修</td>
        <td colspan="3" align="center">保养</td>
      </tr>
      <tr >
        <td width="41" align="center" valign="top">大</td>
        <td width="39" align="center" valign="top">中</td>
        <td width="40" align="center" valign="top">小</td>
        <td width="40" align="center" valign="top">大</td>
        <td width="42" align="center" valign="top">中</td>
        <td width="38" align="center" valign="top">小</td>
        <td width="40" align="center" valign="top">大</td>
        <td width="35" align="center" valign="top">中</td>
        <td width="43" align="center" valign="middle">小</td>
      </tr>
      
      <tr class="rows" id="tr2" class="rows2">
        <td id="tr2_1" rowspan="2" align="center" valign="middle"><p>类</p>
        <p>别</p></td>
        <td height="30" align="center" valign="top">&nbsp;</td>
        <td width="120" align="center" valign="top">&nbsp;</td>
        <td width="93" align="center" valign="top">&nbsp;</td>
        <td width="95" align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
      </tr>
      <tr id="tr2_2" class="rows2">
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
      </tr>
      <tr class="rows" id="tr3">
        <td  id="tr3_1" rowspan="2" align="center" valign="middle"><p>类</p>
        <p>别</p></td>
        <td height="32" align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="top">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
      </tr>
      <tr id="tr3_2">
        <td height="24" align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
        <td align="center" valign="middle">&nbsp;</td>
      </tr>
      <tr class="rows" id="tr4">
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
      </tr>
  <tr class="rows" id="tr5">
        <td>合计</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
        <td>&nbsp;</td>
      </tr>         
    </table>
</div>
<center>
<form action="#" method="post">
<input type="button" id="LB1" value="添加类别行" onclick="addLBrows()"/>
<input type="button" value="添加单行" onclick="addRows()"/>
</form>
<center>
</body>
</html>
我要点击添加类别行后类别的行两行变成三行