using System;

using System.Data;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Xml;

​

public class Program

{

    public static void Main()

    {

        DataTable dt = new DataTable();

        dt.Columns.Add("ID", typeof (int));

        dt.Columns.Add("Name", typeof (string));

        dt.Columns.Add("Result", typeof (string));

        dt.Columns.Add("other", typeof (string));

        dt.Rows.Add(1, "John", "1,2,3,4,5", "b");

        dt.Rows.Add(2, "Mary ", "5,6,7,8", "d");

        dt.Rows.Add(3, "John", "6,7,8,9", "a");

        DataTable dtRsult = dt.Clone();

​

        var distinctRows = dt.DefaultView.ToTable(true, "ID").Rows.OfType<DataRow>().Select(k => k[0] + "").ToArray();

        //foreach (string id in distinctRows)

        foreach (Int32 id in distinctRows)

        {

            var rows = dt.Select("ID = '" + id + "'");

            //var rows = dt.Select("ID = '" + id + "'");

            string value = "";

            string other = "";

            foreach (DataRow row in rows)

            {

                value += row["Result"] + ",";

                other += row["other"];

            }

​

            value = value.Trim(',');

            dtRsult.Rows.Add(id, value, other);

            value = "";

            other = "";

        }

​

        var output = dtRsult;

        foreach (DataRow dr in dtRsult.Rows)

        {

            Console.WriteLine(dr[0] + " --- " + dr[1] + "---- " + dr[2]);

        }

    }

}