private string MaTuTang() { string s = ""; DateTime time = DateTime.Now; string ngay = time.ToString("dd"); string thang = time.ToString("MM"); string nam = time.ToString("yy"); string date = ngay + thang + nam; List <NhanVienDTO> ds = myNhanVienBUL.LayThongTinNhanVien(); if (ds.Count <= 0) { s = "NV_" + date + "_001"; } else { string newstt = ""; int k = ds.Count; int stt = Convert.ToInt32(ds[k - 1].MaNhanVien.ToString().Substring(10, 3)); string checkday = ds[k - 1].MaNhanVien.ToString().Substring(3, 6); if (date == checkday) { int tempstt = stt + 1; if (tempstt <= 9) { newstt = "00" + tempstt.ToString(); } if (tempstt >= 10 && tempstt < 100) { newstt = "0" + tempstt.ToString(); } if (tempstt == 100) { newstt = "100"; } s = "NV_" + date + "_" + newstt; } else { s = "NV_" + date + "_001"; } } return(s); }