Question

我有具体问题。我对SQL不太熟悉，所以这可能是一个愚蠢的问题。我有以下课程

class StructuredResult
{
    public Pay Pay{ get; set; }
    public Processing Processing{ get; set; }
    public Member Member { get; set; }

    public StructuredResult()
    {
    }
}

这是我用

获得此代码的代码

var allPaying = (from pay in Entities.Pays
                join prc in Entities.Processingss on pay.IDCalculation equals cal.IDCalculation
                join mbr in Entities.Members on pay.IDMember equals mbr.IDMember

                where pay.IDMember == IDMember
                orderby prc.DateFrom descending
                select new StructuredResult()
                {
                    Pay = pay,
                    Processing = prc,
                    Member = mbr
                }).ToList();

代码工作正常我改变了在这里发布的东西，也许一些名称更改不行。我需要得到的是：

class StructuredResult
{
    public Pay Pay{ get; set; }
    public Processing Processing{ get; set; }
    public Member Member { get; set; }
    public List<PayDetail> PayDetails { get; set; }

    public StructuredResult()
    {
    }
}

有谁知道这是否可能？付款详细信息与Pay.ID = PayDetail.ID相关联提前致谢

Answer 1

为了使用StructuredResult的{{1}}集合填充PayDetail，您需要使用Group Join。参见：

MSDN on GroupJoin
最后Linq to Entities join vs groupjoin。

所以：

var allPaying = from pay in Entities.Pays
                join prc in Entities.Processingss on pay.IDCalculation equals cal.IDCalculation
                join mbr in Entities.Members on pay.IDMember equals mbr.IDMember
                join d in Entities.PayDetails on pay.IDMember equals d.ID into details

                where pay.IDMember == IDMember
                orderby prc.DateFrom descending

                select new StructuredResult()
                {
                    Pay = pay,
                    Processing = prc,
                    Member = mbr,
                    PayDetails = details
                };

我还建议您使用EF查看导航属性。通过稍微不同地定义类，您将获得更多的功能，而不是更少（例如，不需要编写连接）

MSDN - Entity Framework Relationships and Navigation Properties
MSDN - How to: Navigate Relationships Using Navigation Properties

只是一个小技巧 - 您正在定义一个id中没有逻辑的默认构造函数。如果在实际代码中也是如此，则不需要它。它是自动定义的。

Answer 2

这可能会对您有所帮助：

var allPaying = (from pay in Entities.Pays
                 join prc in Entities.Processingss on pay.IDCalculation equals cal.IDCalculation
                 join mbr in Entities.Members on pay.IDMember equals mbr.IDMember

                 where pay.IDMember == IDMember
                 orderby prc.DateFrom descending
                 select new StructuredResult()
                 {
                     Pay = pay,
                     Processing = prc,
                     Member = mbr,
                     PayDetails = (from pd in Entities.PayDetails
                                   where pd.ID == pay.IDMember
                                   select pd).ToList())
                 }).ToList();

如何检索一个表行和连接到Linq .NET中第一行的行列表

2 个答案: