สอบถามเรื่องการทำ Group By ข้อมูลที่ซ้ำกันในตัว DataTable

            DataTable dt = new DataTable();
            dt.Columns.Add(new DataColumn("ID"));

            DataRow dr = dt.NewRow();
            dr["ID"] = "x001";
            dt.Rows.Add(dr);

            DataRow dr1 = dt.NewRow();
            dr1["ID"] = "x002";
            dt.Rows.Add(dr1);

            DataRow dr2 = dt.NewRow();
            dr2["ID"] = "x001";
            dt.Rows.Add(dr2);

            DataRow dr3 = dt.NewRow();
            dr3["ID"] = "x003";
            dt.Rows.Add(dr3);

            DataRow dr4 = dt.NewRow();
            dr4["ID"] = "x004";
            dt.Rows.Add(dr4);

            DataRow dr5 = dt.NewRow();
            dr5["ID"] = "x002";
            dt.Rows.Add(dr5);
          
            

            var grouped = from table in dt.AsEnumerable()
                          group table by new { IDcol = table["ID"] } into groupby
                          select new
                          {
                              columnValues = groupby.Key
                          };
            string str = string.Empty;
            foreach (var key in grouped)
            {
                str += key.columnValues.IDcol
                str += Environment.NewLine;
            }
            MessageBox.Show(str);

DataTable dt = new DataTable();
            dt.Columns.Add(new DataColumn("ID"));

            DataRow dr = dt.NewRow();
            dr["ID"] = "x001";
            dt.Rows.Add(dr);

            DataRow dr1 = dt.NewRow();
            dr1["ID"] = "x002";
            dt.Rows.Add(dr1);

            DataRow dr2 = dt.NewRow();
            dr2["ID"] = "x001";
            dt.Rows.Add(dr2);

            DataRow dr3 = dt.NewRow();
            dr3["ID"] = "x003";
            dt.Rows.Add(dr3);

            DataRow dr4 = dt.NewRow();
            dr4["ID"] = "x004";
            dt.Rows.Add(dr4);

            DataRow dr5 = dt.NewRow();
            dr5["ID"] = "x002";
            dt.Rows.Add(dr5);
            string str = string.Empty;


            var grouped = dt.AsEnumerable().GroupBy(r => r.Field<string>("ID")).Select(g => new { ID = g.Key , Total = g.Count()});

            foreach (var key in grouped)
            {
                str += key.ID;
                str += " " + key.Total;
                str += Environment.NewLine;
            }
            MessageBox.Show(str);