static void Update()
        {
            string connectStr = "server=127.0.0.1;port=3306;database=mygamedb;user=root;password=root";
            MySqlConnection conn = new MySqlConnection(connectStr);  //并没有去跟数据库建立连接

            try
            {
                conn.Open();   //与MySQL数据库建立连接

                string sql = "update users set username='qqqqqq',password='111111' where id='3'";
                Console.WriteLine(sql);
                MySqlCommand cmd = new MySqlCommand(sql, conn);
                int result = cmd.ExecuteNonQuery();//返回值是数据库中受影响的数据行数
                Console.WriteLine(result);
                Console.WriteLine("已经建立连接");
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());

            }
            finally
            {
                conn.Close();
            }

            Console.ReadKey();
        }