private void btnSanPham_Click(object sender, EventArgs e)
        {
            frmSanPham frm = new frmSanPham();

            frm.Show();
        }
        private void sảnPhẩmToolStripMenuItem_Click(object sender, EventArgs e)
        {
            frmSanPham frm = new frmSanPham();

            frm.ShowDialog();
        }