LEFT JOIN與LINQ用的EntityFramework

Question

我儘量讓使用LINQ左查詢：

public IQueryable<Mutatie> GetMutaties() 
     { 
      var query = (from m in context.Mutatie 
         join d in context.tblDienstverband on m.fkDienstVerbandID equals d.DienstverbandID 
         join med in context.tblMedewerker on d.fkMedewerkerID equals med.MedewerkerID 
         where med.fkKlantID == this.klantId 
         select m).Include(d => d.fkDienstVerbandID); 
      return query; 
     } 

但如何讓這有一個留網址查詢？

謝謝

我有現在這樣的：

var query = (from m in context.Mutatie 
         join d in context.tblDienstverband on m.fkDienstVerbandID equals d.DienstverbandID into grp 
         from d in grp.DefaultIfEmpty() 

         join med in context.tblMedewerker on d.fkMedewerkerID equals med.MedewerkerID into grp1 
         from med in grp.DefaultIfEmpty() 

         where med.fkMedewerkerID == this.klantId 
         select new { m, d, med }); 
      return query; 

Answer 1

應該是這樣的：

注：d和MED爲空，如果沒有行匹配

public IQueryable<Mutatie> GetMutaties() 
{ 
    var query = (from m in context.Mutatie 
       join d in context.tblDienstverband on m.fkDienstVerbandID equals d.DienstverbandID into grp 
       from d in grp.DefaultIfEmpty() 

       join med in context.tblMedewerker on d.fkMedewerkerID equals med.MedewerkerID into grp_med 
       from med in grp_med.DefaultIfEmpty() 

       where med.fkKlantID == this.klantId 
       //select new { m, d, med }; 
       select m; 
    return query; 
}