using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

using System.Xml;

using System.Xml.Linq;

using System.Globalization;

using System.Data;

using System.Data.DataSetExtensions;

public class Program

{

    public static void Main()

    {

        DataTable dt = new DataTable();

​

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

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

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

        dt.Rows.Add(new object[]{1,101,"500"});

        dt.Rows.Add(new object[]{1,102,"600"});

        dt.Rows.Add(new object[]{2,101,"400,500"});     

        dt.Rows.Add(new object[]{2,103,"500,600,700"});

        var result = dt.AsEnumerable()

            .GroupBy(r=>r.Field<int>("StudentId"))

            .Select(c=> 

                    new Student() 

                    {

                        studentId = c.Key, 

                        Books = c.GroupBy(s=>s.Field<int>("bookId"))

                            .Select(b=> 

                                    new Book() 

                                    {

                                        bookId = b.Key, 

                                        pages = b.SelectMany(p=>p.Field<string>("Page").Split(',').Select(int.Parse)).ToList() 

                                    }).ToList()

                    }).ToList();

        foreach(var r in result)

        {

            r.Dump();

        }

    }

}

​

public class Student

{

    public int studentId;

    public List<Book> Books; 

}

​

public  class Book

{   

    public int  bookId;

    public List<int> pages;

}