private void DisplayStudent_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                List <StudentEntityCl> showlist = StudentBALCl.GetAllStudentsBL();
                dataGrid.ItemsSource = showlist;
            }

            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }
        private void Find_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                int             flag   = 0;
                int             id     = Convert.ToInt32(textBox.Text);
                StudentEntityCl entobj = StudentBALCl.SearchStudentBL(id);

                List <StudentEntityCl> showlist = StudentBALCl.GetAllStudentsBL();

                for (int index = 0; index < showlist.Count; index++)
                {
                    if (showlist[index].STUDENTID == id)
                    {
                        flag = 1;
                        break;
                    }
                    else
                    {
                        flag = 0;
                    }
                }

                if (flag == 0)
                {
                    MessageBox.Show("No such student found");
                    Environment.Exit(0);
                }

                // MessageBox.Show(entobj.DATEOFADMISSION.ToString());
                textBox1.Text = entobj.STUDENTNAME;
                textBox2.Text = entobj.CITY;
                textBox3.Text = entobj.COURSE;
                DOA.Text      = entobj.DATEOFADMISSION.ToString();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }