private void button1_Click(object sender, EventArgs e)
{
this.Close();
KhachHang kh = new KhachHang();
kh.Tenkhachhang = tb.Khachhang;
kh.SoDienThoai = tb.Sdt;
kh.Tongsotien = tong;
SQLDataContext db = new SQLDataContext();
db.KhachHangs.InsertOnSubmit(kh);
db.SubmitChanges();
}
