private void But_Click1(object sender, EventArgs e) { bool isEmpty = !lt.Any(); bool check = false; if (isEmpty) { Model1 db = new Model1(); double gia = 0; foreach (Drink j in db.Drink) { if (j.id_Drink == Convert.ToInt32(((Button)sender).Tag)) { gia = j.price; } } lt.Add(new Cart { Id = Convert.ToInt32(((Button)sender).Tag), NameSp = ((Button)sender).Name.ToString(), SoLuong = 1, Tien = gia, }); double total = 0; foreach (Cart i in lt) { total += i.Tien; } textBox1.Text = total.ToString(); dataGridView1.DataSource = null; var l = lt.Select(p => new { p.NameSp, p.SoLuong, p.Tien }); dataGridView1.DataSource = l.ToList();; } else { Model1 db = new Model1(); double gia = 0; foreach (Drink j in db.Drink) { if (j.id_Drink == Convert.ToInt32(((Button)sender).Tag)) { gia = j.price; } } for (int i = 0; i <= lt.Count - 1; i++) { if (String.Compare(lt[i].Id.ToString(), ((Button)sender).Tag.ToString(), true) == 0) { lt[i].SoLuong += 1; lt[i].Tien = gia * lt[i].SoLuong; check = true; } } if (check == false) { lt.Add(new Cart { Id = Convert.ToInt32(((Button)sender).Tag), NameSp = ((Button)sender).Name.ToString(), SoLuong = 1, Tien = gia, }); } double total = 0; foreach (Cart i in lt) { total += i.Tien; } textBox1.Text = total.ToString(); dataGridView1.DataSource = null; var l = lt.Select(p => new { p.NameSp, p.SoLuong, p.Tien }); dataGridView1.DataSource = l.ToList();; } }