Question

我设置了以下实体，我试图查询：

存储
StoreCapability。商店可以有多种功能（例如卖巧克力，很大） - 但不需要有任何功能。
优惠。优惠可能需要多个商店功能才能生效，但不需要任何要求。

Store -[m2m]- StoreCapability -[m2m]- Offer

所以涉及五个表。

我希望能够使用linq获得以下内容：

给出要约，
鉴于商店，可用优惠清单

使用SQL可以从Store，StoreCapability加入Offer，然后按要约和商店分组，只获得count（）等于商品要求数量的商店。但是我不知道从哪里开始使用Linq，因为Entity框架隐藏了许多表。任何人都可以帮我解决这个问题吗？

SQL可能与此类似：

SELECT Offers.Id, offers.Name, Stores.Id, Stores.Name FROM Offers
--join to the capabilities that this offer needs
LEFT OUTER JOIN StoreCapabilityOffers offerRequirements ON Offers.Id = offerRequirements.Offer_Id
--join to stores which have capability
LEFT OUTER JOIN StoreCapabilities ON offerRequirements.StoreCapability_Id = StoreCapabilities.Id
--join to stores
LEFT OUTER JOIN StoreStoreCapabilities storeCap ON offerRequirements.StoreCapability_Id = storeCap.StoreCapability_Id
LEFT OUTER JOIN Stores on storeCap.Store_Id = Stores.Id

GROUP BY Offers.Id, offers.Name, Stores.Id, Stores.Name
-- get stores who have the right number of capabilities so all requirements are all met
HAVING COUNT(*) = (
    select COUNT(*) from StoreCapabilityOffers x where x.Offer_Id = Offers.Id
)

以下实体：

public class Store
{
  public int Id { get; set; }
  public virtual ICollection<StoreCapability> Capabilities { get; set; }
}

public class StoreCapability
{
  public int Id { get; set; }
  public virtual ICollection<Store> Stores { get; set; }
  public virtual ICollection<Offer> Offers { get; set; }
}

public class Offer
{
  public int Id { get; set; }
  public virtual ICollection<StoreCapability> StoreCapabilityRequirements { get; set; }
}

Answer 1

我认为这样的事情应该有效：

鉴于要约，它有效的商店列表：

var stores = from o in context.Offers
             from c in o.StoreCapabilityRequirements
             from s in c.Stores
             where o.Id == 1
             select s;

鉴于商店，提供了一系列优惠：

var offers = from s in context.Stores
             from c in s.Capabilities
             from o in c.Offers
             where s.Id == 1
             select o;

Linq查询有两个很多关系

1 个答案: