public void AutoCodeGenerate() { decimal AlreadyExistData = _CustomerRepository.AlreadyExistCode(); int code = 1; if (AlreadyExistData >= 1) { var GetLastCode = _CustomerRepository.LastExistCode(); if (GetLastCode != null) { code = Convert.ToInt32(GetLastCode.Code); code++; } txtCode.Text = code.ToString("000"); } else { txtCode.Text = "001"; } }