private void buttonSuaDM_Click(object sender, EventArgs e)
        {
            FormChungLoai fcl = new FormChungLoai();

            if (listBoxDM.SelectedIndex != -1)
            {
                fcl.textBoxMaLoai1.Text  = listBoxDM.SelectedItem.ToString().Split('-')[0];
                fcl.textBoxTenLoai1.Text = listBoxDM.SelectedItem.ToString().Split('-')[1];
            }
            if (fcl.ShowDialog() == DialogResult.OK)
            {
                ChungLoai cl = new ChungLoai();
                cl.maLoai  = fcl.textBoxMaLoai1.Text;
                cl.tenLoai = fcl.textBoxTenLoai1.Text;
                if (clbll.KiemTraTonTai(cl.maLoai) == true)
                {
                    if (clbll.SuaChungLoai(cl) > 0)
                    {
                        MessageBox.Show("SỬa Thành công Danh mục");
                        LoadDanhMuc();
                    }
                }
                else
                {
                    MessageBox.Show("Danh mục không tồn tại");
                }
            }
        }
        private void buttonThemDM_Click(object sender, EventArgs e)
        {
            FormChungLoai fcl = new FormChungLoai();

            if (fcl.ShowDialog() == DialogResult.OK)
            {
                ChungLoai cl = new ChungLoai();
                cl.maLoai  = fcl.textBoxMaLoai1.Text;
                cl.tenLoai = fcl.textBoxTenLoai1.Text;
                if (clbll.KiemTraTonTai(cl.maLoai) == false)
                {
                    if (clbll.ThemChungLoai(cl) > 0)
                    {
                        MessageBox.Show("Them Thành công Danh mục");
                        LoadDanhMuc();
                    }
                }
                else
                {
                    MessageBox.Show("Da ton tai danh muc");
                }
            }
        }