using System;

using System.Linq;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        // Student collection

        List<Student> ListOfStudent = new List<Student>() 

        { 

                new Student() {  Id = 1, Name = "Alen", Age = 19, Gender = "Male", Marks = 500, SchoolId = 2 } ,

                new Student() {  Id = 2, Name = "Nick", Age = 15, Gender = "Male", Marks = 200, SchoolId = 3  } ,

                new Student() {  Id = 3, Name = "Niki", Age = 20, Gender = "Female", Marks = 450, SchoolId = 1  } ,

                new Student() {  Id = 4, Name = "Eric", Age = 22, Gender = "Male", Marks = 600, SchoolId = 1 } ,

                new Student() {  Id = 5, Name = "Jane", Age = 18, Gender = "Female", Marks = 800, SchoolId = 2  } ,

                new Student() {  Id = 6, Name = "Bill", Age = 17, Gender = "Male", Marks = 350, SchoolId = 3 } ,

                new Student() {  Id = 7, Name = "Sara", Age = 24, Gender = "Female", Marks = 300, SchoolId = 3  },

                new Student() {  Id = 8, Name = "Sara", Age = 22, Gender = "Female", Marks = 400, SchoolId = 1  } ,

                new Student() {  Id = 9, Name = "Sara", Age = 23, Gender = "Female", Marks = 400, SchoolId = 1  } 

            };

        // School collection

        List<School> ListOfSchool = new List<School>() 

        {

            new School() {Id = 1, Name = "Nevada High School"},

            new School() {Id = 2, Name = "Texas International School"},

            new School() {Id = 3, Name = "Pennsylvania High School"},

        };

        // LINQ Extension Method

        //----------------------

        // Where : The Where operator filters the collection based on a given criteria or expression and returns a new collection.

        var TeenAgeStudent = from student in ListOfStudent

                              where student.Age > 12 && student.Age < 20

                              select student;

​

        Console.WriteLine("Teen age Students:");

        Console.WriteLine("------------------");                  

        foreach(Student student in TeenAgeStudent)

        {           

            Console.WriteLine("{0} - {1}", student.Name, student.Age);

        }

        Console.WriteLine();

        // OrderBy : Sorts the elements in the collection based on specified fields in ascending or decending order.

        var SortByName = from student in ListOfStudent

                                where student.Age > 17

                                orderby student.Name descending

                                select student;

        Console.WriteLine("Order by descending Student name:");

        Console.WriteLine("---------------------------------");

        foreach(Student student in SortByName)

        {

            Console.WriteLine("{0} - {1}", student.Name, student.Age);

        }

        Console.WriteLine();

        // ThenBy : Used for second level sorting in ascending or descending order.

        var SortByNameThenByAge = ListOfStudent.Where(student => student.Age > 17).ToList().OrderByDescending(student => student.Name).ThenBy(student => student.Age);

        Console.WriteLine("Order by descending Student name then by age:");

        Console.WriteLine("---------------------------------------------");

        foreach(Student student in SortByNameThenByAge)

        {

            Console.WriteLine("{0} - {1}", student.Name, student.Age);

        }

        Console.WriteLine();

        // Join : The Join operator joins two collections based on a key.

        // Inner join, Group join, Left outer join

        var JoinStudentWithSchool = from student in ListOfStudent

                                    join school in ListOfSchool on student.SchoolId equals school.Id

                                    select new 

                                    {

                                        SchoolName = school.Name, StudentName = student.Name

                                    };

        Console.WriteLine("Join School with Student");

        Console.WriteLine("------------------------");

        foreach(var item in JoinStudentWithSchool)

        {

            Console.WriteLine("{0} - {1}", item.SchoolName, item.StudentName);

        }

        Console.WriteLine();

        // 

    }

}

​

// Student class

public class Student

{

​

    public int Id { get; set; }

    public string Name { get; set; }

    public int Age { get; set; }

    public string Gender { get; set; }

    public decimal Marks { get; set; }

    public int SchoolId { get; set; }

}

​

// School class

public class School

{

    public int Id { get; set; }

    public string Name { get; set; }

}