private void phòngBanToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmPhongBan f = new frmPhongBan();

            f.ShowDialog();
        }
 private void phòngBanToolStripMenuItem_Click(object sender, EventArgs e)
 {
     frmPhongBan f = new frmPhongBan();
     f.ShowDialog();
 }