public void tinhtien(int id)
{
Dsmonans ds = new Dsmonans();
giatien = 0;
List <DataRow> list = ds.show_dsmonan(id_hoadon).AsEnumerable().ToList();
foreach (var item in list)
{
giatien = giatien + int.Parse(item[1].ToString()) * int.Parse(item[2].ToString());
}
txt_thanhtien.Text = giatien.ToString() + " VNĐ ";
}
public void load_dsmonan(int id, int soban, string tenkh)
{
data_dsmonan.RowHeadersVisible = false;
Dsmonans ds = new Dsmonans();
txt_thanhtien.Text = giatien.ToString();
data_dsmonan.DataSource = ds.show_dsmonan(id);
id_hoadon = id;
sobanan = soban;
tenkhachhang = tenkh;
enable_control(false);
null_data_control();
tinhtien(id);
}