private void chon_Click(object sender, EventArgs e)
{
Button b = sender as Button;
var pr = b.Parent;
var num = pr.Controls.Find("SL", false).First() as NumericUpDown;
if (num.Value > 0)
{
Detail.AddOrUpdateDetail(Convert.ToInt32(b.Tag.ToString()), ID_Bill, Convert.ToInt32(num.Value));
pr.BackColor = Color.Yellow;
dataGridView1.DataSource = Bill.GetBill(ID_Bill);
dataGridView1.Columns["Price"].DefaultCellStyle.Format = "#,##0";
dataGridView1.Columns["Total"].DefaultCellStyle.Format = "#,##0";
textBox2.Text = string.Format("{0:#,##0}", Bill.TotalByBill(ID_Bill));
}
}