private void LoginLogin_Click(object sender, EventArgs e) { if (Username.Text.Length == 0) { MessageBox.Show("Please enter username.", "Access denied", MessageBoxButtons.OK, MessageBoxIcon.Information); } else if (Password.Text.Length == 0) { MessageBox.Show("Please enter password.", "Access denied", MessageBoxButtons.OK, MessageBoxIcon.Information); } else { try { StudentServices service = new StudentServices(); List <string> loginUser = service.LoginAccess(Username.Text, Password.Text); Password.Text = ""; if (loginUser.Count > 0) { if (Username.Text == "giaovu") { ManagerForm newForm = new ManagerForm(); Visible = false; newForm.ShowDialog(); Visible = true; } else { StudentForm newForm = new StudentForm(loginUser); Visible = false; newForm.ShowDialog(); Visible = true; } } else { MessageBox.Show("Wrong username or password.", "Access denied", MessageBoxButtons.OK, MessageBoxIcon.Stop); } } catch (Exception ex) { MessageBox.Show(ex.Message); } } }