// 排序 private int Sort1(DAL.StudentEntity x, DAL.StudentEntity y) { if (string.IsNullOrEmpty(x.DiplomaNumber)) { x.DiplomaNumber = ""; } if (string.IsNullOrEmpty(y.DiplomaNumber)) { y.DiplomaNumber = ""; } return(x.DiplomaNumber.CompareTo(y.DiplomaNumber)); }