從mysql數據庫將圖片加載到圖片框時出錯。 的NullReferenceException

Question

我正在嘗試從數據庫中獲取圖像並顯示到圖片框中。 我的代碼如下

private void getImage()
{
    using (MySqlConnection conn = new MySqlConnection(connectionManager.connectionString))
    {
        try
        {
            conn.Open();

            string query = "SELECT 'Image' FROM student_img WHERE ID =  @ID";

            MySqlCommand cmd = new MySqlCommand(query, conn);

            int id = 10;
            cmd.Parameters.AddWithValue("@ID", id);

            var da = new MySqlDataAdapter(cmd);
            var ds = new DataSet();
            da.Fill(ds, "Image");
            int count = ds.Tables["Images"].Rows.Count;

            if (count > 0)
            {
                var data = (Byte[])(ds.Tables["Images"].Rows[count - 1]["Image"]);
                var stream = new MemoryStream(data);
                picLogo.Image = Image.FromStream(stream);
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show("Connection Error!\n" + ex.Message, "Error Message",
                    MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }

}

但是我收到NullReferenceException錯誤。 我也有另一種方法，也許我可以以某種方式使用它，但是我不確定如何從數據庫中獲取數據，因為我是C＃新手。

public Image byteArrayToImage(byte[] byteArrayIn)
{
    MemoryStream ms = new MemoryStream(byteArrayIn);
    Image returnImage = Image.FromStream(ms);
    return returnImage;
}

Answer 1

設法解決問題，不得不改變

圖片

至

圖片

private void getImage()
        {
            using (MySqlConnection conn = new MySqlConnection(connectionManager.connectionString))
            {
                try
                {
                    conn.Open();

                    string query = "SELECT Image FROM student_img WHERE ID =  @ID";

                    MySqlCommand cmd = new MySqlCommand(query, conn);

                    int id = 10;
                    cmd.Parameters.AddWithValue("@ID", id);

                    var da = new MySqlDataAdapter(cmd);
                    var ds = new DataSet();
                    da.Fill(ds, "Image");
                    int count = ds.Tables["Image"].Rows.Count;

                    if (count > 0)
                    {
                        var data = (Byte[])(ds.Tables["Image"].Rows[count - 1]["Image"]);
                        var stream = new MemoryStream(data);
                        picLogo.Image = Image.FromStream(stream);
                    }

                }
                catch (Exception ex)
                {
                    MessageBox.Show("Connection Error!\n" + ex.Message, "Error Message",
                            MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }

        }