连接必须有效且打开错误 [英] Connection must be valid and open error

问题描述

我收到错误消息:启动此程序时，连接必须有效并打开.我在Google上搜索，仅发现2个人有相同的错误.有可能解决这个问题吗?谢谢

I'm getting error: Connection must be valid and open when I start this program. I searched on google and only found 2 people that have the same error. Is it possible to fix this ?? Thx

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Data.Odbc;
using System.Data.Sql;
namespace WindowsFormsApplication1
{
static class Program
{
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        string connectionString = "Server=localhost;Uid=root;Pwd=******;Database=testing;";
        MySql.Data.MySqlClient.MySqlConnection connection = new MySql.Data.MySqlClient.MySqlConnection(connectionString);

        connection.Open();

        string insertQuery = "ALTER TABLE `user` ADD lol INT";
        MySql.Data.MySqlClient.MySqlCommand myCommand = new MySql.Data.MySqlClient.MySqlCommand(insertQuery);
        myCommand.ExecuteNonQuery();
        connection.Close();
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);
        Application.Run(new Form1());
    }
}
}

推荐答案

您需要告诉您的命令有关您的连接对象的信息. 将连接参数添加到此行:

You need to tell your command about your connection object. Add the connection parameter to this line:

MySql.Data.MySqlClient.MySqlCommand myCommand = new MySql.Data.MySqlClient.MySqlCommand(insertQuery, connection);

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