using System;

using System.Collections.Generic;

using System.Data;      

using System.Xml.Serialization;

using System.Linq;

using System.Data.Linq;

using System.Data.DataSetExtensions;

​

public class Program

{

    public static void Main()

    {

        using (DataTable dt = new DataTable("MyDataTable"))

        {

            // Add two columns.

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

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

            // Add some test data.

            Random rnd = new Random();

            for(int i = 0; i < 7; i++)

            {

                DataRow dr = dt.NewRow();

                dr["Id"] = rnd.Next(1, 4);

                dr["Name"] = "Row-" + (i + 1);

                dt.Rows.Add(dr);

            }

            Console.WriteLine("All rows:");

            PrintResults(dt.AsEnumerable());

            var results = dt.AsEnumerable().GroupBy(x => (int)x["Id"]).Select(g => g.First());

            Console.WriteLine("Distinct rows with linq:");

            PrintResults(results);          

        }

    }

    private static void PrintResults(IEnumerable<DataRow> rows)

    {

        foreach(var row in rows)

        {

            Console.WriteLine(String.Format("Id: {0}, Name: {1}", (int)row["Id"], (string)row["Name"]));

        }   

    }

}