Linq 先进行分组，在进行排序（选取某一个人的最新的一条记录）



var asd = from a in context.v_ydyl_execdrug
                              group  new { a.drug_name,a.INPATIENT_NO, a.USE_TIME }  by a.INPATIENT_NO into g
                              orderby g.FirstOrDefault().USE_TIME
                              select new
                              {
                                  INPATIENT_NO = g.FirstOrDefault().INPATIENT_NO,
                                  USE_TIME=g.FirstOrDefault().USE_TIME,
                                  drug_name=g.FirstOrDefault().drug_name
                              };

 var assdaf = asd.ToList();