using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        IList<Student> studentList = new List<Student>() 

        { 

            new Student() { StudentID = 1, StudentName = "John", Age = 18, StandardID = 1 } ,

            new Student() { StudentID = 2, StudentName = "Steve",  Age = 21, StandardID = 1 } ,

            new Student() { StudentID = 3, StudentName = "Bill",  Age = 18, StandardID = 2 } ,

            new Student() { StudentID = 4, StudentName = "Ram" , Age = 20, StandardID = 2 } ,

            new Student() { StudentID = 5, StudentName = "Ron" , Age = 21 } 

        };

​

        IList<Standard> standardList = new List<Standard>() 

        { 

            new Standard(){ StandardID = 1, StandardName="Standard 1"},

            new Standard(){ StandardID = 2, StandardName="Standard 2"},

            new Standard(){ StandardID = 3, StandardName="Standard 3"}

        };

        var studentsGroupByStandard = from s in studentList

                              where s.StandardID > 0

                              group s by s.StandardID into sg

                              orderby sg.Key 

                                    select new { sg.Key, sg };

​

        foreach (var group in studentsGroupByStandard)

        {

            Console.WriteLine("StandardID {0}:", group.Key);    

            group.sg.ToList().ForEach(st => Console.WriteLine(st.StudentName ));

        }

    }

}

​

public class Student

{ 

    public int StudentID { get; set; }

    public string StudentName { get; set; }

    public int Age { get; set; }

    public int StandardID { get; set; }

}

​

public class Standard

{ 

    public int StandardID { get; set; }

    public string StandardName { get; set; }

}

​

​