private void btnLogin_Click(object sender, EventArgs e)
        {
            if (txtusername.Text == "")
            {
                MessageBox.Show("Enter username please!");
            }

            else if (txtpassword.Text == "")
            {
                MessageBox.Show("Enter password please!");
            }
            else
            {
                if (readerLogin.Checked)
                {
                    ReaderBUS readerBUS           = new ReaderBUS();
                    var       readerInfoDataTable = readerBUS.readAll();

                    foreach (DataRow row in readerInfoDataTable.Rows)
                    {
                        if (row["username"].ToString() == txtusername.Text &&
                            row["password"].ToString() == txtpassword.Text)
                        {
                            MessageBox.Show("Hello Reader ^.^");
                            var reader = new Reader(txtusername.Text, true);
                            this.Hide();
                            reader.ShowDialog();
                            this.Close();
                        }
                        else
                        {
                            MessageBox.Show("[!] Wrong username or password typed in. Try again");
                        }
                    }
                }
                else
                {
                    AdministratorBUS adminBUS = new AdministratorBUS();
                    var adminInfoDataTable    = adminBUS.readAll();

                    foreach (DataRow row in adminInfoDataTable.Rows)
                    {
                        if (row["username"].ToString() == txtusername.Text &&
                            row["password"].ToString() == txtpassword.Text)
                        {
                            AdministratorDTO admin = new AdministratorDTO();
                            admin.MaNV     = row["manv"].ToString();
                            admin.HoTen    = row["hoten"].ToString();
                            admin.DiaChi   = row["diachi"].ToString();
                            admin.SDT      = row["sdt"].ToString();
                            admin.DOB      = Convert.ToDateTime(row["dob"].ToString());
                            admin.CMND     = row["cmnd"].ToString();
                            admin.Email    = row["email"].ToString();
                            admin.NLT      = Convert.ToDateTime(row["ngaylapthe"].ToString());
                            admin.NVLapThe = row["nvlapthe"].ToString();
                            admin.BangCap  = row["bangcap"].ToString();
                            admin.ChucVu   = Int32.Parse(row["chucvu"].ToString());
                            admin.UserName = row["username"].ToString();
                            admin.Password = row["password"].ToString();

                            if (GetAdminId != null)
                            {
                                GetAdminId(admin.MaNV);
                            }

                            if (admin.ChucVu == 0)
                            {
                                var managerdb = new ManagerDashboard();
                                managerdb.manv = admin.MaNV;
                                managerdb.pos  = admin.ChucVu;
                                this.Hide();
                                managerdb.ShowDialog();
                                this.Close();
                            }
                            else if (admin.ChucVu == 1)
                            {
                                var readerdb = new ReaderManagement();
                                readerdb.librarianid = admin.MaNV;
                                this.Hide();
                                readerdb.ShowDialog();
                                this.Close();
                            }
                            else if (admin.ChucVu == 2)
                            {
                                var bookdb = new BookManagement();
                                bookdb.stockkeeperid = admin.MaNV;
                                this.Hide();
                                bookdb.ShowDialog();
                                this.Close();
                            }
                            else
                            {
                                MessageBox.Show("Punishment");
                            }
                        }
                    }
                    //MessageBox.Show("[!] Wrong username or password typed in. Try again");
                }
            }
        }