变量未返回正确信息 [英] variables not returning correct information

问题描述

我不确定为什么我的变量pin，firstName和balance没有给出正确的值.当我运行该应用程序并选择一个帐号时，我可以输入图钉，并且messageBox显示欢迎"，但不显示成员的姓名.然后，当我按下平衡按钮时，每次都会打印0.我不确定为什么会这样.

I''m not sure why my variables pin, firstName, and balance aren''t giving correct values. When I run the app and pick an account number, I am able to enter a pin, and the messageBox displays welcome, but not the member''s name. Then, when I hit the balance button, it prints 0 everytime. Im not sure why this is happening.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using SQLDll;

namespace WindowsFormsApplication14
{

    public partial class Form1 : Form
    {
        private Connection myConnection;
        private Statement myStatement;
        private ResultSet myResultSet;
        String databaseURL = "http://www.boehnecamp.com/phpMyAdmin/razorsql_mysql_bridge.php";
        private string pin ,firstName, userAccountNumber;
        private double balance;
        private double withdraw = 0;
        private double deposit = 0;
        bool buttonClicked, buttonClicked2;

        public Form1()
        {
            InitializeComponent();
            
            try
            {
                //connect to database
                SQL sql = new SQL();
                myConnection = sql.getConnection(databaseURL);
                //create Statement for executing SQL
                myStatement = myConnection.createStatement(databaseURL);
                loadAccountNumbers();
                updateBalance();
            }
            catch (Exception)
            {
                Console.WriteLine("Cannot connect to database server");
            }
            //close statement and database connection 
           myStatement.close();
           myConnection.close();
        }
        private void Form1_Load(object sender, EventArgs e)
        {   
        }

        
        private void retrieveAccountInformation()
        {
            //get account info
            try
            {
                myResultSet = myStatement.executeQuery("SELECT pin, " +
               "firstName, balanceAmount FROM accountInformation " +
               "WHERE accountNumber = '" + userAccountNumber + "'");

                //get next result
                if (myResultSet.next())
                {
                    pin = myResultSet.getString("pin");
                    firstName = myResultSet.getString("firstName");
                    balance = myResultSet.getDouble("balanceAmount");
                }
                myResultSet.close(); //close myResultSet
            }//end try
            catch (Exception)
            {
                Console.WriteLine("Error in retrieveAccountInformation");
            }
        }// end method retrieveAccountInformation

        //update database after withdrawing
        private void updateBalance()
        {
            //update balance in database
            try
            {
                myStatement.executeUpdate("UPDATE accountInformation" +
                               " SET balanceAmount = " + balance + " WHERE " +
                               "accountNumber = '" + userAccountNumber + "'");

            }
            catch (Exception)
            {
                Console.WriteLine("Error in updateBalace");
            }
        }//end method updateBalance

        private void accountNumberComboBox_SelectedIndexChanged(object sender, EventArgs e)
        {
            accountNumberComboBox.Enabled = false;
            numberTextField.Text = " ";
            messageTextArea.Text = "Enter your PIN #.";
            buttonDone.Enabled = true;

        }
        private void buttonEnter_Click(object sender, EventArgs e)
        {
            retrieveAccountInformation();
                numberTextField.Text = " ";
                buttonEnter.Enabled = false;
                buttonBalance.Enabled = true;
                buttonWithdraw.Enabled = true;
                buttonDeposit.Enabled = true;
                messageTextArea.Text = "Welcome" + firstName;
                updateBalance();

            
        }

        private void buttonBalance_Click(object sender, EventArgs e)
        {
            retrieveAccountInformation();
            updateBalance();
            messageTextArea.Text=(balance.ToString());
            //display balance to messageTextArea
        }


   
    }
}

推荐答案

你好，

代替这个，

Hello,

Instead of this,

//get next result
               if (myResultSet.next())
               {
                   pin = myResultSet.getString("pin");
                   firstName = myResultSet.getString("firstName");
                   balance = myResultSet.getDouble("balanceAmount");
               }

试试这个，

Try this,

//get next result
               if (myResultSet.ReadFirst())
               {
                   pin = myResultSet.getString("pin");
                   firstName = myResultSet.getString("firstName");
                   balance = myResultSet.getDouble("balanceAmount");
               }

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