private void button6_Click(object sender, EventArgs e) { string tensach = textBox3.Text; int dongia = int.Parse(textBox4.Text); int soluongton = int.Parse(textBox5.Text); string tacgia = textBox6.Text; int matheloai = int.Parse(textBox7.Text); Sach_DTO sach = new Sach_DTO(tensach, dongia, soluongton, tacgia, matheloai); Sach_BUS.ThemMotSachMoi(sach); dataGridView2.DataSource = Sach_BUS.LoadDanhSachTatCaSach(); }