private void btnIn_Click(object sender, EventArgs e)
        {
            ds = hh.dsCuaHang;
            InCuaHang f = new InCuaHang();

            f.ShowDialog();
        }
        private void btnInTimKiem_Click(object sender, EventArgs e)
        {
            ds = hh.Tim(txtTenHang.Text);
            InCuaHang f = new InCuaHang();

            f.ShowDialog();
        }