Question

我有一个Java项目可供学校使用。我使用sql和JFrame并且当我尝试从订单中删除（或编辑）记录时，我有3个表（客户，订单，汽车），所有来自订单的记录都被删除而不是一个。我猜我的SQL查询有问题。所以，如果有人能告诉我我的错误那就太好了。 :)

这是我的代码：

class DeleteOrder implements ActionListener{

    @Override
    public void actionPerformed(ActionEvent arg0) {
        // TODO Auto-generated method stub

        conn = DBConnector.getConnected();

        String selectCustomerId = "select cus_id from customers where lname=? and ";
           String selectCarId = "select car_id from cars where model=?";

           String selectedCustomer = customersCombo.getSelectedItem().toString();
            String selectedCar = carsCombo.getSelectedItem().toString();

        String sql="delete from Orders where " + selectCustomerId + selectCarId;

        try {
            state = conn.prepareStatement(sql);
            state.setString(1, selectedCustomer);
            state.setString(2, selectedCar);
            state.execute();
            getAllDataFromOrders();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            try {
                conn.close();
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }


    }

}//end Delete ORder

Answer 1

你只是添加两个数字，我真的不知道为什么。我想而不是：

String sql="delete from Orders where " + selectCustomerId + selectCarId;

你应该写：

String sql="delete from Orders where cus_id =" + selectCustomerId +" and car_id = "+ selectCarId;

为什么我的sql表中的所有记录都被删除了？

1 个答案: