如何把select下拉框的值传到id中实现代码

<!-- 
EOT; 
if($step==1){ 
print <<<EOT --> 
<div class="main"> 
<form name="form_order" method="post" action="?action=$atc" enctype="multipart/form-data"> 
<div class="shopcartbox"> 
<div class="shopcart2"> 
<!-- 
EOT; 
$total_all=0; 
$jinbi_all=0; 
foreach($listdb AS $name=>$array){ 
$total=0; 
$jinbi=0; 
print <<<EOT 
--> 
<ul class="u1"> 
<li class="l1"><div><input type="checkbox" name="" id="" checked="checked" /> 全选</div></li> 
<li class="l2">商品</li> 
<li class="l3">返积分</li> 
<li class="l4">数量</li> 
<li class="l5">单价</li> 
<li class="l6">总价</li> 
</ul> 
<!-- 
EOT; 
foreach($array AS $rs){ $ 
rs[picurl]=$rs[picurl]?$rs[picurl]:"$webd[www_url]/images/default/nopic.webp"; 
$rs[picurl]=tempdir($rs[picurl]); 
@extract($db->get_one("SELECT content FROM {$_pre}content_$rs[mid] WHERE id=$rs[id]")); 
$content=preg_replace('/<([^<]*)>/is',"",$content); //把HTML代码过滤掉 
$content=preg_replace('/ |　| /is',"",$content); //把多余的空格去除掉 $content= get_word($content,100); 
$total+=$rs[price2]; 
$total_all+=$rs[price2]; 
$jinbi+=$rs[jinbi2]; 
$jinbi_all+=$rs[jinbi2]; 
print <<<EOT 
--> 
<ul class="u2" id="tr$rs[id]"> 
<li class="l1"><input type="checkbox" name="" id="" checked="checked" /></li> 
<li class="l2"><a href="bencandy.php?city_id=$rs[city_id]&fid=$rs[fid]&id=$rs[id]" class="pic" target="_blank"><img src="$rs[picurl]"height="90" onError="this.src='$webdb[www_url]/images/default/nopic.webp'"/></a><h3><a href="bencandy.php?city_id=$rs[city_id]&fid=$rs[fid]&id=$rs[id]" target="_blank">$rs[title]</a></h3><p>$rs[content]</p></li> 
<li class="l3">0分</li> 
<li class="l4">{$rs[num]}</li> 
<li class="l5"><font>{$rs[price]}</font>元</li> <li class="l6"><font id="showid$rs[id]" class="shows$rs[uid]">{$rs[price2]}</font>元</li> </ul> 
<!-- 
EOT; 
}print <<<EOT 
--> 
<ul class="u3"> 
<div class="fr"> 
<p class="p1"> 
运送方式： 
<!-- 
EOT; 
if($rs[youfei]=="1"){print <<<EOT 
--> 
<select id="collect" name="postdb[youfei]" onchange="Add(this.value,'total$rs[uid]')"> 
<option value='10'>快递:10元</option> 
<option value='20'>EMS:20元</option> 
<option value='50'>平邮:50元</option> 
</select> 
<SCRIPT LANGUAGE="JavaScript"> 
<!-- 
function changenum(price,type,id,uid){ 
price=parseFloat(price); 
num = parseInt($("#numid"+id).val()); 
if(type==1){ //增加 
num++; } 
else if(type==-1){ //减少 
num--; } 
else if(type==0){ //删除 
num=0 } 
if(type!=0 && num==0){ 
alert('数量不能小于1,若不想购买,请选择删除'); 
num=1; } 
$("#numid"+id).val(num); 
$("#showid"+id).html(changeTwoDecimal(String(num*price))); obj=$(".shows"+uid); 
thispice = 0; 
for(i=0;i<obj.size();i++){ 
thispice+=parseFloat(obj.eq(i).html()); } 
$("#total"+uid).html(thispice); if(type==0){ 
$.get("join.php?type=setcookie&cid="+id+"&num="+0); $("#tr"+id).hide(); }else{ 
$.get("join.php?type=setcookie&cid="+id+"&num="+num+"&"+Math.random()); } obj2 = $(".totalprice"); 
if(obj2.size()>1){ thispice = 0; for(i=0;i<obj2.size();i++){ 
thispice+=parseFloat(obj2.eq(i).html()); } 
$("#total_all").html(thispice); } } 
function changeTwoDecimal(x){ 
var f_x = parseFloat(x); 
if(isNaN(f_x)){ 
alert('function:changeTwoDecimal->parameter error'); 
return false; } 
var f_x = Math.round(x*100)/100; return f_x; } 
function Add(m,id){ document.getElementById(id).innerHTML = parseInt(document.getElementById(id).getAttribute("total")+parseInt(m)) //--> </SCRIPT> 
<!-- 
EOT; } 
print <<<EOT 
--> 
</p> 
<p class="p2"><strong>店铺商品合计： 
</strong>(含运费) <font id="total$rs[uid]" class="totalprice">$total</font>元</p> 
</div> 
<div class="fl"> 
<p class="p1"><stron>卖家：{$rs[username]}</strong></p> 
<p class="p2">给卖家留言：<textarea name='postdb[content]' id='atc_content' >$rsdb[content]</textarea></p> 
</div> 
</ul> 
<!-- 
EOT; }print <<<EOT 
--> 
<!-- 
EOT; 
if(count($listdb)>1){ 
print <<<EOT 
--> 
<ul class="u4"><div><strong>商品总价：</strong>(含运费) <font id="total_all">$total_all</font>元</div></ul> <!-- EOT; } 
print <<<EOT 
--> 
</div> 
</div> 
<div class="clear20"></div> <div class="shoppostbox"> 
<div class="shoppostdiv"> 
<div class="shopinfo"> 
<p><span>实付款：</span> 
<!-- 
EOT; 
if(count($listdb)>1){ 
print <<<EOT 
--> 
<font id="total$rs[uid]" class="totalprice">$total_ll</font>元 
<!-- 
EOT; } 
else{print <<<EOT 
--> 
<font id="total$rs[uid]" class="totalprice">$total</font>元 
<!-- 
EOT; 
}print <<<EOT 
--> </p> {$address_selects} 
</div> 
</div> 
<div class="shop_postbtn"> 
<input type="submit" name="imageField" id="imageField" class="shop-submit" value=" " /> <input type="hidden" name="fid" value="$fid"> <input type="hidden" name="id" value="$id"> <input type="hidden" name="cid" value="$cid"> <input type="hidden" name="postdb[title]" id="atc_title" size="50" value="$infodb[title]"> </div> 
<!-- 
EOT; 
if($job=='edit'){print <<<EOT 
--> 
<SCRIPT LANGUAGE="JavaScript"> 
<!-- 
$(document).ready(function(){ 
$("#othermore").show();$("#dobutton").hide(); 
}); 
//--> 
</SCRIPT> 
<a href="?action=del&id=$id&cid=$cid&fid=$rsdb[fid]" onClick="return confirm('你确认要删除吗?');">删除</a> 
<!-- 
EOT; 
}print <<<EOT 
--> 
</div> 
<script language="JavaScript"> 
<!-- 
function chooseAddress(selObj){ 
value = selObj.options[selObj.selectedIndex].value; 
if(value=='-1'){ 
ifHideMoreTr(false); } 
else{ ifHideMoreTr(true); 
} 
} 
function ifHideMoreTr(type){ 
var arr = ["username","phone","mobphone","email","qq","postcode","address" ]; 
$("#othermore input").each(function (i){ 
if(jQuery.inArray(this.name.replace(/postdb/[order_([/w]+)/]/, "$1"),arr)!=-1){ 
obj=$(this).parent().parent(); 
if(type==true){ 
obj.hide() 
}else{ obj.show() 
} 
} 
}); 
} 
$(document).ready(function(){ 
sObj = $("#choose_Address"); 
if(sObj.get(0).options.length==1||"$job"=="edit"){ 
sObj.parent().parent().hide 
ifHideMoreTr(false); 
} 
else{ ifHideMoreTr(true); 
} 
}); 
//--> 
</script> 
</form> 
</div> 
<!-- 
EOT; 
} print <<<EOT 
--> 
<div class="clear20"> 
</div> 
</div> 
<!-- 
EOT; 
?> 
--> 

<select id="collect" name="postdb[youfei]" onchange="Add(this.value,'total$rs[uid]')"> 
<option value='10'>快递:10元</option> 
<option value='20'>EMS:20元</option> 
<option value='50'>平邮:50元</option> 
</select>