using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var employees = new List<Employee>

            {

                new Employee { Id =1, Name = "foo", DeptId = 1001 },

                new Employee { Id =2, Name = "bar", DeptId = 1000 },

                new Employee { Id =3, Name = "xyz", DeptId = 1002 }

            };

​

            var departments = new List<Department>

            {

                new Department { Id = 1000, Name = "HR" },

                new Department { Id = 1001, Name = "IT" },

                new Department { Id = 1002, Name = "R&D" },

                new Department { Id = 1003, Name = "Finance" },

                new Department { Id = 1004, Name = "Production" },

            };

​

​

            var result = from d in departments

                         join e in employees

                         on d.Id equals e.DeptId into es

                         from x in es.DefaultIfEmpty()

                         where x == null

                         select new Department { Id = d.Id, Name = d.Name};

​

            foreach (var item in result)

            {

                Console.WriteLine("Department Id: {0}",item.Id);

                Console.WriteLine("Name: {0}",item.Name);

            }

    }

    public class Employee

    {

        public int Id { get; set; }

        public string Name { get; set; }

        public int DeptId { get; set; }

    }

​

    public class Department

    {

        public int Id { get; set; }

        public string Name { get; set; }

    }

}