I was like’ this looks like a candidate for pivot, but it requires that the result be put in exactly on row. I cheated and sent him back this code. He was happy.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace ConsoleApplication5

{

    class Program

    {

        static void Main(string[] args)

        {

                var week_days = new List<Sales>();

                week_days.Add(new Sales {Sequence = 1, Day = "Sun", Amount = 23});

                week_days.Add(    new Sales {Sequence = 2, Day = "Mon", Amount = 18});

                week_days.Add(    new Sales {Sequence = 3, Day = "Tue", Amount = 30});

                week_days.Add(    new Sales {Sequence = 4, Day = "Wed", Amount = 15}); 

                week_days.Add(    new Sales {Sequence = 5, Day = "Thu", Amount = 20});

                week_days.Add(    new Sales {Sequence = 6, Day = "Fri", Amount = 08});

                week_days.Add(    new Sales {Sequence = 7, Day = "Sat", Amount = 0});

                //Before transpose

                foreach(var day in week_days)

                  Console.WriteLine("{0}  {1}  {2}", day.Sequence, day.Day, day.Amount);

                var tr = from row in  week_days

                            group row by "SALES" into g

                            where g.FirstOrDefault() != null

                            select new

                    {

                            DAY = g.Key,

                            Sun = g.Where(sales => sales.Day == "Sun").Sum(sales => sales.Amount),

                            Mon = g.Where(sales => sales.Day == "Mon").Sum(sales => sales.Amount),

                            Tue = g.Where(sales => sales.Day == "Tue").Sum(sales => sales.Amount),

                            Wed = g.Where(sales => sales.Day == "Wed").Sum(sales => sales.Amount),

                            Thu = g.Where(sales => sales.Day == "Thu").Sum(sales => sales.Amount),

                            Fri = g.Where(sales => sales.Day == "Fri").Sum(sales => sales.Amount),

                            Sat = g.Where(sales => sales.Day == "Sat").Sum(sales => sales.Amount)

                    };

            foreach(var day in tr)

                  Console.Write("{0} {1} {2} {3} {4} {5} {6}", day.Sun, day.Mon, day.Tue, day.Wed, day.Thu, day.Fri, day.Sat);

            Console.ReadLine();

        }

    }

    public class Sales

    {

        public int Sequence {get; set;}

        public string Day { get; set;}

        public double Amount {get; set;}

    }

}

I should mention that I tried this code on my favourite ORM DataObjects.NET and I was not disappointed.