为什么合计功能和更新数量功能实现不了？

Question

<%    
               String sql="select * from cart ";
               PreparedStatement pstat=conn.prepareStatement(sql);
               ResultSet rs=pstat.executeQuery();
             //商品展示
               String id,name,price,num,count,IMG;     
               while(rs.next()){               
               id=rs.getString("SP_NO").trim();
               name=rs.getString("SP_NAME").trim();
               price=rs.getString("SP_PRICE").trim();
               num=rs.getString("BUY_NUM").trim();
               count=rs.getString("COUNT").trim();
               IMG=rs.getString("IMG").trim();  
               session.setAttribute("name1",name);
               %>
               <tr>
               <td class="checkbox"><input class="check" type="checkbox" /></td>
               <td style="padding-left:20px;padding-right:20px;"><img width=90px height=90px src="<%=IMG%>" ></td>
               <td style="width:300px;text-align:center;"><%=name %></td>
               <td style="width:150px;"><%=price %></td> 
               <td style='width:150px;'><input type=number style="width:60px;" value="<%=num%>" onChange=updateNum(id,this.value,price) ></td>
               <td style='width:150px;' class="count"><%=count%></td>
               <td style='width:150px;'><a href="buy.jsp?op=del&id=<%=id %>" style="color:#000000;text-decoration: none;">删除商品</a></td>
               </tr>
               <%} %> 

 <div id="money">
         <table  id="all" width="300px;">                       
             <thead>  
                 <tr ><th colspan="2" style="text-align:left;">购物车合计</th></tr>     
             </thead>   
             <tbody >                                
                 <tr>  <td >购物车小计 </td> <td><span class="getPrice" ></span></td></tr>             
                 <tr>  <td >运费</td>       <td>免费运输</td></tr>
                 <tr>  <td >购物车合计</td>  <td ><span class="getPrice" ></span></td> </tr>                 
             </tbody>                        
        </table> 
        <button class="list" style="margin-left:-200px;" name="clean">结账</button>  
       </div>     

function getPrices(){
          //获得各个商品的单独总价
          var counts = document.getElementsByClassName("count");
          var sum = 0;
          for( i=0;i < counts.length;i++){
              sum += Number(counts[i].innerText);         
          }
          return sum;       
       }
       //将getPrices函数获得dom元素将计算出的总价写入对应的td表格
       var cartPrice = getPrices();
       function writePrice(sum){
           var prices = document.getElementsByClassName("getPrice");
           for( i=0;i<prices.length;i++){
              prices[i].innerHtml = sum;
           }       
       }

function updateNum(id,num,price){
          //调用已定义好的writePrice函数计算出购物车的总价格，并输入到页面对应的表格上
          writePrice(cartPrice);
          //定义一个新的url将页面中的值传入buy.jsp业务处理页面
          var url="buy.jsp?op=update&id="+id+"&num="+num2+"&price="+price;
          //window.Location方法让当前页面跳转到指定的地址
          window.location=url;       
       }
       function initPrice(){
          writePrice(cartPrice);       
       }
       initPrice();

<%       
//更新商品信息功能       
       if(op.equals("update")){
           int id=Integer.parseInt(request.getParameter("id"));
           int num2=Integer.parseInt(request.getParameter("num2"));
           double price=Double.parseDouble(request.getParameter("price"));
           
           String sql="update cart set BUY_NUM =?,COUNT=? where sp_NO=?";
           PreparedStatement pstat=conn.prepareStatement(sql);           
           
           pstat.setInt(1,num2);
           pstat.setString(2,new Double(price*num2).toString());
           pstat.setInt(3,id);
           pstat.executeUpdate();           
         
           pstat.close();         
           conn.close();
           
           response.sendRedirect("cart.jsp");    
       };     %>