连接必须有效且打开错误
我收到错误:当我启动此程序时,连接必须有效并打开。 我在谷歌搜索,只发现2个人有相同的错误。 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 { /// /// The main entry point for the application. /// [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()); } } }
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);
您的命令没有连接assignet。 尝试将连接传递给命令的构造函数,如下所示:
MySql.Data.MySqlClient.MySqlCommand myCommand = new MySql.Data.MySqlClient.MySqlCommand(insertQuery, connection);