Grouping on DataSet Table AsEnumerable

You can use LINQ to perform GroupBy operations on a DataTable. Here is a short example:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace LINQGroupBy
{
    class Program
    {
         static void Main(string[] args)
        {
             string cn = "server=(local);database=northwind;Integrated Security=SSPI";
           SqlConnection conn = new SqlConnection(cn);
           SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM EMPLOYEES", conn);
           DataSet ds = new DataSet();
            da.Fill(ds);
            var grps = from n in ds.Tables[0].AsEnumerable() group n by n["ReportsTo"] into grp select grp;
             foreach (var g in grps)
               Console.WriteLine( g.FirstOrDefault()["LastName"]);
        }
     }
}