如何将在textfield中输入的值填充到表中

Question

我正在尝试为客户生成账单。当我在表单中添加项目并单击添加按钮时，我希望它创建表格并显示账单。但它不能正常工作。我试图使用sql查询，但它只显示2项，有时空白。当有3个项目插入数据库时​​。请任何人都能告诉我哪里出错了。

  <tr>
  <td height="517"><form name="form1" method="post" action="">
  <table width="400" border="0" align="center" cellpadding="10" cellspacing="0">
    <tr>
      <td colspan="2"><div align="center">Add item Details </div></td>
    </tr>
    <tr>
      <td width="117">Item Name</td>
      <td width="243"><input name="itemName" type="text" id="itemName">
      </td>
    </tr>
    <tr>
      <td>Quantity</td>
      <td><input name="qty" type="text" id="qty"></td>
    </tr>
    <tr>
      <td>Price </td>
      <td><input name="price" type="text" id="price"></td>
    </tr>
    <tr>
      <td>Vat </td>
      <td><input name="vat" type="text" id="vat"></td>
    </tr>
    <tr>
      <td></td>
      <td><input type="submit" name="Submit" value="Add"></td>
    </tr>
  </table>
</form>   
 <p align="center">Bill Record</p>
  <p align="center">&nbsp; </p>
  <table width="70%"  border="0" align="center" cellpadding="10" cellspacing="0">
  <tr>
    <th>Item Name</th>

    <th>Quantity</th>
    <th>Price</div></th>
     <th>Vat</th>
   <th>total</th>

  </tr>
   <% double grandTotal=0;
      try
      {
        Statement st=con.createStatement();
        ResultSet rs=st.executeQuery("select * from bill where cname='"+session.getAttribute("cname")+"' order by datetime asc");
        while(rs.next())
        {
  %>
  <tr>
    <td><%=rs.getString("itemName")%></td>
    <td><%=rs.getString("qty")%></td>
    <td><%=rs.getString("price")%></td>
    <td><%=rs.getString("vat")%></td>
            <td><%= rs.getString("total") %></td>
    <% grandTotal+=Double.parseDouble( rs.getString("total"));%>
  </tr>
      <% 
                 }   %>
   <tr>
      <td></td>
      <td></td>
      <td></td>
      <td>grandTotal</td>
      <td><%= grandTotal %> </td>
    </tr>
    <%  con.close();
    }
     catch(Exception e)
    {
        out.println("Error: "+e);
    }
  %>

  </table>
 </tr>

以下是我在数据库中添加值的代码。

 <% 
    if(request.getMethod().equals("POST"))
    {
       String itemName="";
        int qty;
        double price,vat,total;
        grandTotal=0;
        boolean exists=false;
         itemName=request.getParameter("itemName");
         qty=Integer.parseInt(request.getParameter("qty"));
          price=Double.parseDouble(request.getParameter("price"));
         vat=Double.parseDouble(request.getParameter("vat"));
         total=price+vat;

         SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
          Date date = new Date();
   try
        {
              Statement st=con.createStatement();
                st.executeUpdate("INSERT into bill values('"+session.getAttribute("cname")+"','" + dateFormat.format(date) + "','"+itemName+"','"+qty+"','"+price+"','"+vat+"','"+total+"','"+grandTotal+"')");
          out.println("<script> alert('Item Added Successfully')</script>");


        }