Linq to SQL（實體框架）按工作分組編號

Question

在Linq to SQL中，可以按周工作週數進行分組，而不是從每年的幾周開始，例如1/1/2016在12周的同一周/ 31/2015這是不同一週的一年（但它是在同一個物理周，如果你願意）

Answer 1

這是一個按工作周分組的例子，工作周從最早的日期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(); 
}