c# - MySQLDataReader 未将任何数据加载到所示表单上的指定位置

Question

我在将信息从数据库加载到标签和图片框中时遇到问题。我认为我的代码可以正确执行我想要的操作，但我猜不是，因为它不起作用。下面是我正在使用的代码。对于数据库中的图片列，我存储图片的路径，而不是实际的 blob。如果您需要更多相关信息，请询问。

代码:

private void AirSpace_Shown(object sender, EventArgs e)
    {
        string connectionString = "datasource=localhost;port=3306;username=Admin;password=August211989";
        Login login = new Login();
        using (MySqlConnection conn = new MySqlConnection(connectionString))
        {
            using (MySqlCommand cmd = conn.CreateCommand())
            {
                string select = "SELECT username, email, premium, picture FROM userinfo.users WHERE username = @username;";
                //                        (1)      (2)     (3)      (4)
                conn.Open();
                cmd.CommandText = select;
                cmd.Parameters.AddWithValue("@username", login.UsernameTextBox.Text);
                using (MySqlDataReader Reader = cmd.ExecuteReader())
                {

                    while (Reader.Read())
                    {
                        //Set the user's profile picture to the user's profile picture.
                        ProfilePicture.Load(Reader.GetString(4));
                        //Set the username to the user's username
                        Username.Text = Reader.GetString(1);
                        //Set the app version to the user's version
                        if (Reader.GetString(3) == "1")
                        {
                            AppVersionLabel.Text = "Premium";
                        }
                        else
                        {
                            AppVersionLabel.Text = "Free";
                        }
                    }
                }
            }
        }

Answer 1

你可以试试这个。这看起来也是一个登录代码，所以我会添加逻辑，如果你循环超过一个，它会抛出一个错误，因为应该只有 1 个结果。

While(Reader.Read()){
   //Set the user's profile picture to the user's profile picture.
   string UserProfilePictureLocation = Reader.GetString(3);
   ProfilePicture.Load(UserProfilePictureLocation);
   //Set the username to the user's username
   Username.Text = Reader.GetString(0);
   //Set the app version to the user's version
   if (Reader.GetString(2) == "1")
   {
        AppVersionLabel.Text = "Premium";
   }
   else
   {
        AppVersionLabel.Text = "Free";
   }
}