Linq使用GroupBy筛选数据

     StringBuilder sb = new StringBuilder();      



     List<IGrouping<string, modle>> listRepeat = modelList.GroupBy(l => l.IDCode).Where(g => g.Count() > 1).ToList();

           if (listRepeat.Count() > 0)

           {

               foreach (IGrouping<string, modle> data in listRepeat)

                   sb.AppendFormat("您输入了相同的身份证号/组织机构代码\\\"{0}\\\"！\\r\\n", data.Key);

           }