public void LodeRoll()
{
try
{
var subject = _infoManager.GetStudentId();
dropdownRoll.DataSource = subject;
dropdownRoll.DataTextField = "Roll";
dropdownRoll.DataValueField = "Id";
dropdownRoll.DataBind();
dropdownRoll.SelectedIndex = -1;
}
catch (Exception e)
{
lblMessege.Text = e.Message;
}
}