您好，我正在尝试执行查询，以便将数据从一个表复制到另一个表，这是 project.purchaseorder 至 project.processingactualgrn 我尝试的mysql查询如下：
插入project.processingactualgrn（pono，podate，orderingqty，receivedqty，balanceqty）选择pono，podate，quantity作为orderingqty，（quantity-（quantity-2））作为receivedqty，（quantity-2）作为来自project.purchaseorder的balanceqty，其中pono=1212；
在上面的查询中，我使用了值
在程序中，我使用占位符，使用preparedstatement执行查询用户输入的值 ex-(Quantity-2) AS BalanceQty in this '2' 必须存储在数据库中

protected void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
RequestDispatcher rd = null;

String pno = request.getParameter("PONo");
int p = Integer.parseInt(pno);
String receivedQty1 =request.getParameter("ReceivedQty1");
int Rqty1= Integer.parseInt(receivedQty1);
String receivedQty2 =request.getParameter("ReceivedQty2");
int Rqty2= Integer.parseInt(receivedQty2);

Connection conn = null;
try {
    Class.forName("com.mysql.jdbc.Driver");
    conn = DriverManager.getConnection("jdbc:mysql://localhost:3306", "root", "dinga");

    PreparedStatement ps = conn.prepareStatement("Insert into project.processingactualgrn (PODate,PONo,OrderingQty,ReceivedQty,BalanceQty) Select PODate,PONo,Quantity AS OrderingQty,(Quantity-(Quantity-?) )AS ReceivedQty,(Quantity-?) AS BalanceQty  from project.purchaseorder where PONo=?");
    ps.setInt(1,Rqty1);
    ps.setInt(2,Rqty2);
    ps.setInt(3,p);
    System.out.println("value of ps"+ps);
    int rs = ps.executeUpdate();
    System.out.println("value of ps"+ps);
    if(rs!=0){
        rd = request.getRequestDispatcher("view/sucess.html");
        rd.forward(request, response);
    }

} catch (SQLException e) {
} catch (ClassNotFoundException e) {
} finally {
    try {
        if (conn != null) {
            conn.close();
        }
    } catch (SQLException ex) {
    }
}
}
}