JSTL assignment problem

I have two tables, an order form, a merchandise table , the two are many relationship .

now intend to display a table on one page , the form displays the order record , using JSTL tag , as follows

     <table >
        <thead>
          <tr>
            <th>订单编号</th>
            <th>桌号</th>
            <th>下单时间</th>
            <th>总价</th>
          </tr>
        </thead>
        <tbody>
        <c:forEach items="${orderlist}" var="tbl">
          <tr>
            <td>${tbl.id}</td>
            <td>${tbl.tabletbl.id}</td>
            <td>${tbl.orderTime}</td>
            <td>
            <!-- 
               这里要怎么写啊怎么写，没有思路。。
  
               这里对应的是订单的总价，应该将订单里面的商品set集合循环遍历，取出每一条商品的价格，  
               然后相加显示在这个单元格中
  
               循环是这个样子写:(orderdetailtbls是商品的set集合)
  
               <c:forEach items="${tbl.orderdetailtbls}"  var="od_list">
                  然后在这里把${od_list.price}相加，可是相加的数据要放在哪里？
               </c:forEach>
  
            -->
            </td>
         .....
         ......
        </table>
  

======================


roughly at that question , the sum of the value placed where ? Or how to write his words, the younger rookie , very grateful !
------ Solution ---------------------------------------- ----
outside the loop definition:

  <c:set var="a" value="0"></c:set>
  

loop :

  <c:set var="a" value="${a+od_list.price}"></c:set>
  

final output
$ {a}

Try
------ For reference only -------------------------------- -------
thanks, upstairs you can !