连接必须有效且打开错误

Question

我收到提示:连接必须是有效和打开,当我启动该程序.我搜索谷歌和只发现2人有相同的错误.有可能解决这个问题吗？谢谢

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());
    }
}
}

Answer 1

您需要告诉您的命令有关您的连接对象.将连接参数添加到此行:

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