private void btnLogin_Click(object sender, EventArgs e) { try { string uname = txtUsername.Text; string pwd = txtPassword.Text; Account account = accountData.CheckLogin(uname, pwd); if (account == null) { MessageBox.Show("Check your username or password again"); } else { UserID = account.ID; if (account.role == 0) { this.Hide(); Thread t = new Thread(new ThreadStart(ShowAdminForm)); t.SetApartmentState(ApartmentState.STA); t.Start(); this.Close(); } else if (account.role == 1) { this.Hide(); Thread t = new Thread(new ThreadStart(ShowCashierForm)); t.SetApartmentState(ApartmentState.STA); t.Start(); this.Close(); } else { MessageBox.Show("Invalid Role"); } } } catch (Exception ex) { MessageBox.Show(ex.Message); } }