public void ProcessLogin() { int result; result = dn.Check_User(txtUser.Text, txtPass.Text); if (result == 1000) { MessageBox.Show("Sai " + lblUsername.Text + " or " + lblPass.Text); return; } else if (result == 2000) { MessageBox.Show("Tai khoan bi khoa !!"); return; } LuuThongTin.tendn = txtUser.Text.Trim(); LuuThongTin.manv = dn.getMaNV(txtUser.Text); frmMain frm = new frmMain(); frm.ShowDialog(); }