Linq to SQL (Entity Framework) group by work Week number

Question

In Linq to SQL is it possible to group by Week Number of Work week, not weeks from year, for example 1/1/2016 is in the same week of 12/31/2015 it is not the same week of the year (but it is in the same physical week if you will)

Answer 1

Here is an example of grouping by the work week, with work weeks numbered from the oldest date in MyTable

using(var ctx = new MyEntities())
{
    DateTime firstDate = ctx.MyTable.OrderBy(x => x.Date).First().Date;
    var dates = ctx.MyTable.OrderBy(x => x.Date).Select(x => new { iVal = SqlFunctions.DateDiff("week", firstDate, x.Date), date = x.Date}).ToList();
    var datesGrouped = ctx.MyTable.OrderBy(x => x.Date).Select(x => new { iVal = SqlFunctions.DateDiff("week", firstDate, x.Date), date = x.Date}).GroupBy(x => x.iVal).ToList();
    Console.WriteLine("Ungrouped:");
    dates.ForEach(x => Console.WriteLine("Week #: " + x.iVal + " Date: " + x.date));
    Console.WriteLine("Grouped:");
    datesGrouped.ForEach(x => Console.WriteLine("Week #: " + x.Key + " Date: " + x.First().date));
    Console.ReadLine();
}