linq 集合按照多列进行distinct

List<TaskBatch> sourceList = (from c in BatchCollecion

                                              group c by new

                                                  {

                                                      c.CustomId,

                                                      c.OutsourcingDate,

                                                      c.ServiceId

                                                  } into grp

                                              select grp.First()).ToList();

或者

List<TaskBatch> sourceList = BatchCollecion.GroupBy(x => new { x.CustomId, x.ServiceId, x.OutsourcingDate }).Select(x => x.First()).ToList();