如果包含图像，如何检查数据库

Question

这是我的代码

private void readimagefromdb()

   connection.Open();
   OleDbCommand command = new OleDbCommand();
   command.Connection = connection;
   string query = "select * from StudentInformation where [StudentID] = " + txtStudentID.Text + "";
   command.CommandText = query;
   OleDbDataReader read = command.ExecuteReader();

if (picturebox.Image == null)
{
   txtStudentFN.Text = (read["Firstname"].ToString());
}

if (picturebox.Image != null)
{
     txtStudentFN.Text = (read["Firstname"].ToString());

     byte[] image = (byte[])(read["Image"]);    
     MemoryStream ms = new MemoryStream(image);
     StudentPicture.Image = System.Drawing.Image.FromStream(ms);
}

当我的数据没有图片时我收到错误错误：无法将对象类型system.dbnull转换为类型systembyte

我这样做是为了防止错误，每次我添加一个没有图片的新数据..我可以无错误地阅读。抱歉我的英文不好