private void button3_Click_1(object sender, EventArgs e)
        {
            frmupdatemdsn frm = new frmupdatemdsn();

            frm.Show();
            frm.textBox1.Text = txtInvoiceNo.Text;
        }
        private void toolStripMenuItem6_Click(object sender, EventArgs e)
        {
            frmupdatemdsn frm = new frmupdatemdsn();

            frm.Show();
        }