void NapSinhVien() { DataTable dt = new DataTable(); bus = new BUS_Diem(); dt = bus.showdata_SinhVien(); var item = new Dictionary <string, string>(); foreach (DataRow dr in dt.Rows) { item.Add(dr["MaSV"].ToString(), dr["MaSV"].ToString() + " - " + dr["HoSV"].ToString() + " " + dr["TenSV"].ToString()); } cbMaSV.DataSource = new BindingSource(item, null); cbMaSV.DisplayMember = "Value"; cbMaSV.ValueMember = "Key"; }