using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        // Student collection

        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 } 

        };

        var studentsGroupByStandard = studentList

            .Where(s => s.StandardID > 0)

            .GroupBy(s => s.StandardID)

            .OrderBy(sg => sg.Key)

            .Select(sg => new { sg.Key, sg });

        var studentsGroupByStandard1 = 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; }     

}

​