private void toolStripBtnNhapKho_Click(object sender, EventArgs e)
        {
            Form_PhieuNhap f = new Form_PhieuNhap("NV01");

            this.Hide();
            f.ShowDialog();
            this.Show();
        }
        private void button4_Click(object sender, EventArgs e)
        {
            Form_PhieuNhap form = new Form_PhieuNhap("NV010");

            this.Hide();
            form.ShowDialog();
            this.Show();
        }