using System;

using System.Linq;

using System.Xml;                   

using System.Xml.Linq;

using System.Collections; 

using System.Collections.Generic;

using System.Data;

using System.Data.DataSetExtensions;

using System.Data.Linq;

using System.Text;

using System.Text.RegularExpressions;

using System.Xml.Serialization; 

using System.IO;

using System.Globalization;

using System.Diagnostics;

using System.Collections.Concurrent;

​

public class Program

{

    public static void Main(string[] args)

    {

         DataTable dt = new DataTable();

            dt.Columns.Add("First Name");

            dt.Columns.Add("Middle Name");

            dt.Columns.Add("Last Name");

        dt.Rows.Add("A3", "B3", "C3");

            dt.Rows.Add("A", "B", "C");

            dt.Rows.Add("A1", "B1", "C1");

            dt.Rows.Add("A2", "B2", "C2");

            dt.Rows.Add("A4", "B4", "C3");

        var newTable = dt.AsEnumerable()

            .OrderBy(x=>x.Field<string>("Last Name"))

            .ThenBy(x=>x.Field<string>("First Name"))

            .ThenBy(x=>x.Field<string>("Middle Name")).CopyToDataTable();

        newTable.AsEnumerable().Select(x=>string.Join(",",x.ItemArray)).Dump();

​

    }

}

​

​