private void StudentInsertForm_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'libraryDataSet1.Student' table. You can move, or remove it, as needed.
            // this.studentTableAdapter.Fill(this.libraryDataSet1.Student);
            label7.Hide();

            // TODO: This line of code loads data into the 'sessionDataSet.Session' table. You can move, or remove it, as needed.
            this.sessionTableAdapter.Fill(this.sessionDataSet.Session);
            SessionComboBox.SelectedValue = 0; DepartmentComboBox.SelectedValue = 0;
            label4.Hide(); label5.Hide(); label6.Hide(); label16.Hide(); label15.Hide();
            this.Height = 650; label9.Hide(); label11.Hide(); label12.Hide();
            StudentAddForm.Hide();
            label8.Hide();

            StudentGridView.ForeColor = Color.Black;
            LoadStudentGridView();


            using (var con = new SqlConnection(@"data source=.\SQLEXPRESS;DATABASE=Library ;Integrated Security=true;"))

            {
                var cmd = new SqlCommand("select DepartmentShortName,DepartmentFullName from Department", con);
                con.Open();
                var reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    try
                    {
                        var    departmenShortName = reader.GetString(0);
                        var    departmenFullName  = reader.GetString(1);
                        string departmenName      = "";
                        departmenName = departmenShortName != "" ? departmenShortName : departmenFullName;
                        DepartmentComboBox.Items.Add(departmenName);
                    }
                    catch (Exception exception)
                    {
                        MessageBox.Show(exception.Message);
                    }
                }
            }
            exitAddToolStripMenuItem.Enabled = false;
        }
        private void exitAddToolStripMenuItem_Click(object sender, EventArgs e)
        {
            exitAddToolStripMenuItem.Enabled = false;
            addToolStripMenuItem.Enabled     = true;

            StudentAddForm.Hide();
            this.Height = 650;

            StudentGridView.Show();
            SearchButton.Show();
            StudentSearctBox.Show(); label10.Show();

            StudentDeleteButton.Show();
            label11.Hide();
            label12.Hide();
            FirstPageButton.Show();
            NextPageButton.Show();
            PreviousButton.Show();
            LastPageButton.Show();
        }