无法连接到使用我的窗口的应用程序的在线数据库。 （C＃的WinForms） [英] Can't connect to an online database using my window application. (C# winforms)

问题描述

我注册了一个免费的网络托管帐户。
该网站提供的MySQL数据库，我想用我的Windows应用程序来访问它，但我无法连接到服务器。请考虑我的代码：

I signed up for an account for a free web hosting. The site provides MySQL databases and I'm trying to access it using my windows application but I can't connect to the server. Please consider my code:

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 MySql.Data.MySqlClient;

namespace MySql
{
    public partial class Form1 : Form
    {
        BackgroundWorker bg = new BackgroundWorker();
        string MyConString = "SERVER=209.51.195.117;" + // MySQL host: sql100.0fees.net
                "DATABASE=mydb;" +                      // IP: 209.51.195.117
                "UID=myusername;" +     // not really my username
                "PASSWORD=mypassword;"; // and password

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            bg.DoWork += new DoWorkEventHandler(bg_DoWork);
            bg.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bg_RunWorkerCompleted);
        }

        void bg_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            button1.Enabled = true;
        }

        void bg_DoWork(object sender, DoWorkEventArgs e)
        {
            string status = String.Empty;
            MySqlConnection connection = new MySqlConnection(MyConString);
            try
            {
                connection.Open();
                if (connection.State == ConnectionState.Open)
                    lblStatus.Text = "Connected";
                else
                    lblStatus.Text = "No connection";
            }
            catch (Exception x)
            {
                lblStatus.Text = x.Message;
            }
        }

        private void button1_Click(object sender, EventArgs e)
        {
            lblStatus.Text = "Connecting... please wait.";
            button1.Enabled = false;
            bg.RunWorkerAsync();
        }
    }
}

有没有可能接我适用于在线数据库？ ？或者有没有在我的代码中的错误

Is it possible to connect my application to an online database? Or are there errors in my code?

顺便说一句，这正在生产的错误消息：无法连接到任何指定的MySQL主机

By the way, this the error message being produced: Unable to connect to any of the specified MySQL hosts.

推荐答案

除非你有对服务器的完全控制，你不能暴露mysql服务到网上。 （;有可能是例外差不多）出于安全原因，所有的免费托管这一限制被强加的。除非你提供服务器访问数据的Web服务，则无法远程访问数据库。

Unless you have full control over the server, you can't expose the mysql service to the web. This restriction is imposed by (almost; there might be exceptions) all free hosters for security reasons. Unless you provide a webservice on the server to access data, you can't access the database remotely.

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