using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        List<User> users = new List<User>

            {

                new User { Id =1, Name = "Steve", Age = 21 },

                new User { Id =2, Name = "Jack", Age = 17 },

                new User { Id =3, Name = "Alice", Age = 25 },

                new User { Id =4, Name = "Harry", Age = 14 }

            };

​

            List<UserDetails> details = new List<UserDetails>

            {

                new UserDetails { UId =1, Feature = "Height", Value = "70"},

                new UserDetails { UId =2, Feature = "Height", Value = "65"},

                new UserDetails { UId =2, Feature = "Eyes", Value = "Blue"},

                new UserDetails { UId =4, Feature = "Height", Value = "51"},

                new UserDetails { UId =3, Feature = "Hair", Value = "Brown"},

                new UserDetails { UId =1, Feature = "Eyes", Value = "Green"},

            };

​

            var result = from user in users

                         join detail in details.GroupBy(x => new { x.UId, x.Feature })

                         on user.Id equals detail.Key.UId into g

                         select new

                         {

                             Id = user.Id,

                             Name = user.Name,

                             Age = user.Age,

                             Height = g.FirstOrDefault(z => z.Key.Feature == "Height") != null ? g.First(z => z.Key.Feature == "Height").First().Value : String.Empty,

                             Eyes = g.FirstOrDefault(z => z.Key.Feature == "Eyes") != null ? g.First(z => z.Key.Feature == "Eyes").First().Value : String.Empty,

                             Hair = g.FirstOrDefault(z => z.Key.Feature == "Hair") != null ? g.First(z => z.Key.Feature == "Hair").First().Value : String.Empty,

                         };

​

            Console.WriteLine("Id\tName\tAge\tHeight\tEyes\tHair");

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

            foreach (var item in result)

            {

                Console.WriteLine("{0}\t{1}\t{2}\t{3}\t{4}\t{5}",item.Id,item.Name,item.Age,item.Height,item.Eyes,item.Hair);

            }

    }

}

​

public class User

    {

        public int Id { get; set; }

        public string Name { get; set; }

        public int Age { get; set; }

    }

​

    public class UserDetails

    {

        public int UId { get; set; }

        public string Feature { get; set; }

        public string Value { get; set; }

    }