关于dt分组、计数、排序的实例

  #region table去重复求和
                     var query = dt.Rows.Cast<DataRow>()
                         .OrderByDescending(n => n["OPERATION_TIME"])
                       .GroupBy(
                      s => new
                      {
                          MATERIAL_CODE = Convert.ToString(s["MATERIAL_CODE"]),
                          MATERIAL_NAME = Convert.ToString(s["MATERIAL_NAME"]),
                          STORAGE_STYLE = Convert.ToString(s["STORAGE_STYLE"]),
                          STORAGE_SIGN = Convert.ToString(s["STORAGE_SIGN"])
                      })
                      .Select(group => new
                      {
                          group.Key.MATERIAL_CODE,
                          group.Key.MATERIAL_NAME,
                          group.Key.STORAGE_STYLE,
                          group.Key.STORAGE_SIGN,
                          REMARK = group.First().Field<string>("REMARK"),
                          OPERATION_TIME = group.First().Field<string>("OPERATION_TIME"),
                          STORAGE_NUM = group.Sum(x => Convert.ToInt32(x["STORAGE_NUM"]))
                      });

                     if (query.ToList().Count > )
                     {
                         dtNew = dt.Clone();
                         query.ToList().ForEach(q =>
                         {
                             DataRow drNew = dtNew.NewRow();
                             drNew["MATERIAL_CODE"] = q.MATERIAL_CODE;
                             drNew["MATERIAL_NAME"] = q.MATERIAL_NAME;
                             drNew["REMARK"] = q.REMARK;
                             drNew["STORAGE_NUM"] = q.STORAGE_NUM;
                             drNew["STORAGE_STYLE"] = q.STORAGE_STYLE;
                             drNew["OPERATION_TIME"] = q.OPERATION_TIME;
                             drNew["STORAGE_SIGN"] = q.STORAGE_SIGN;
                             dtNew.Rows.Add(drNew);
                         });
                     }
                     #endregion