如何将group by和join从sql server转换为linq?

你所做的是在代码中的内部连接,在sql中,你已经编写了left-join,所以我将使用left-join

var res=(from tr in dbContext.Transacao
         join td in dbcontext.TransacaoDivisao
         on tr.CodTransacao equals td.CodTransacao
         into r11
         from r1 in r11.DefaultIfEmpty()
         join sp in dbcontext.ServicosPrestado
         on r1.CodServicoPrestado equals sp.CodServicosPrestado
         into r22
         from r2 in r22.DefaultIfEmpty()
         join s in dbContext.CodServico
         on r2.CodServico equals s.CodServico
         into r33 
         from r3 in r33.DefaultIfEmpty()
         select new {r1,r3})
         .GroupBy(x=>x.r3?.Nome)
         .Select(x=>new 
                    {
                      Total=x.Sum(z=>(z.r1==null?0:z.r1.Valor)),
                      Servico Prestado=x.Key
                    })
         .OrderByDescending(x=>x.Key)
         .ToList();