private void btnThem_Click(object sender, EventArgs e) { if (KiemTra() == "") { NhaXuatBanDTO NXB = new NhaXuatBanDTO(); NXB.MaNXB = txtMaNXB.Text; NXB.TenNXB = txtTenNXB.Text; NXB.DiaChi = txtDiaChi.Text; NXB.DienThoai = txtDienThoai.Text; if (NhaXuatBanBUS.ThemNXB(NXB) == true) { txtMaNXB.Text = NhaXuatBanBUS.GetIDNXB(); txtTenNXB.ResetText(); txtDiaChi.ResetText(); txtDienThoai.ResetText(); LoadData(); } else { MessageBox.Show("Thêm thất bại.", "Lỗi", MessageBoxButtons.OK, MessageBoxIcon.Error); } } else { MessageBox.Show(string.Format("{0}", KiemTra()), "Lỗi", MessageBoxButtons.OK, MessageBoxIcon.Error); } }