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();
}
