private void btThem_Click(object sender, EventArgs e) { string MaMA = "MA0001"; while (XuLyDuLieu.kiemtratontai(MaMA)) { if (dem < 10) { MaMA = "MA000" + dem.ToString(); } else if (dem < 100) { MaMA = "MA00" + dem.ToString(); } else if (dem < 1000) { MaMA = "MA0" + dem.ToString(); } else { MaMA = "MA" + dem.ToString(); } dem++; } DataRow cn = dsMM.NewRow(); cn[0] = MaMA; cn[1] = txtTen.Text; cn[2] = txtDonGia.Text; cn[3] = txtThongTin.Text; cn[4] = "Dessert"; cn[5] = cbbChiNhanh.SelectedValue; dsMM.Rows.Add(cn); XuLyDuLieu.ghiDuLieu("MON_AN", dsMM); loadDSMM(); }