private void TSMI_Sanpham_Click(object sender, EventArgs e)
        {
            frmSanpham frmsp = new frmSanpham();

            frmsp.ShowDialog();
        }
        private void btn_formSanpham_Click(object sender, EventArgs e)
        {
            frmSanpham sp = new frmSanpham();

            sp.ShowDialog();
        }