Linq to SQL - 精确的关系除法

Question

下面的 Linq-to-SQL 查询，当前结果：

NotSupportedException：本地序列不能在查询运算符的 LINQ to SQL 实现中使用，但 Contains 运算符除外。

使用 linq to SQL 时，在 linq 中执行精确关系除法过滤器的典型方法似乎不可用。

在下面的查询中，我们看到两次尝试使用 except 子句来过滤掉任何在提供的范围内没有 ID 的记录。

有谁知道除了更改为使用存储过程或推迟 Expect 过滤器以进一步过滤返回的列表之外还需要做什么？

该部分具体是

&&
(additionalServiceIDs == null || additionalServiceIDs.Count == 0 ||  
    !(AdditionalServices.Where(ads => p.ReferenceNumber == ads.FK_Provider_ReferenceNumber).Select(ad => ad.FK_ServiceList_ID).Except(additionalServiceIDs).Any())
) //  *ONLY* records that match the provided list of additionalServiceIDs, no more - no less (aka. Exact Relational Division)
&&
(additionalServiceIDs == null || additionalServiceIDs.Count == 0 ||  
    !(AdditionalNeeds.Where(adn => p.ReferenceNumber == adn.FK_Provider_ReferenceNumber).Select(an => an.FK_ServiceList_ID).Except(additionalNeedsIDs).Any())
) //  *ONLY* records that match the provided list of additionalServiceIDs, no more - no less (aka. Exact Relational Division)

在：

List<int> additionalServiceIDs = new List<int>(){40,42}; 
List<int> establishmentIDs = new List<int>() {}; 
List<int> additionalNeedsIDs = new List<int>(){}; 
bool advertisedOnly = true; 
bool Internal = true;
string providerTypeCode = "";
List<string> settingTowns = new List<string>() {};

var sqlResultsList = (from p in Providers
                          join po in ProviderOverviews on p.ReferenceNumber equals po.FK_Provider_ReferenceNumber into p_po
                          from p_po_LeftOuter in p_po.DefaultIfEmpty() // left outer join
                          join ad in AdditionalServices on p.ReferenceNumber equals ad.FK_Provider_ReferenceNumber into p_ad
                          from p_ad_LeftOuter in p_ad.DefaultIfEmpty() // left outer join
                          join sp in SchoolPickUps on p.ReferenceNumber equals sp.FK_Provider_ReferenceNumber into p_sp
                          from p_sp_LeftOuter in p_sp.DefaultIfEmpty() // left outer join
                          join an in AdditionalNeeds on p.ReferenceNumber equals an.FK_Provider_ReferenceNumber into p_an
                          from p_an_LeftOuter in p_an.DefaultIfEmpty() // left outer join
                          join il in Inspections on p.ReferenceNumber equals il.FK_Provider_ReferenceNumber into p_il
                          from p_il_LeftOuter in p_il.DefaultIfEmpty() // left outer join

                          join sl in SchoolLists on p_sp_LeftOuter.FK_SchoolList_SchoolID equals sl.SchoolID into sp_sl
                          from sp_sl_LeftOuter in sp_sl.DefaultIfEmpty() // left outer join

                          join nl in NeedLists on p_an_LeftOuter.FK_NeedsList_ID equals nl.ID into an_nl
                          from an_nl_LeftOuter in an_nl.DefaultIfEmpty() // left outer join

                          join svl in ServiceLists on p_ad_LeftOuter.FK_ServiceList_ID equals svl.ID into ad_svl
                          from ad_svl_LeftOuter in ad_svl.DefaultIfEmpty() // left outer join

                          join ptl in ProviderTypeLists on p.FK_ProviderTypeList_ID equals ptl.ID 

                          where

                                        (string.IsNullOrEmpty(providerTypeCode) || ptl.Code.ToLower() == providerTypeCode)
                                        &&
                                        p.Advertise == advertisedOnly
                                        &&
                                        (settingTowns == null || settingTowns.Count == 0 || settingTowns.Contains(p.SettingTown.ToLower())) // allow for no parameters being passed
                                        &&
                                        (establishmentIDs == null || establishmentIDs.Count == 0 || establishmentIDs.Contains(p_sp_LeftOuter.FK_SchoolList_SchoolID)) // allow for no parameters being passed
                                        &&
                                        (Internal == true || p.RegistrationStatus == "ACTV")// if internal = false then add filter ..  RegistrationStatus =  'ACTV'
                                        &&
                                        (additionalServiceIDs == null || additionalServiceIDs.Count == 0 ||  
                                            !(AdditionalServices.Where(ads => p.ReferenceNumber == ads.FK_Provider_ReferenceNumber).Select(ad => ad.FK_ServiceList_ID).Except(additionalServiceIDs).Any())
                                        ) //  *ONLY* records that match the provided list of additionalServiceIDs, no more - no less (aka. Exact Relational Division)
                                        &&
                                        (additionalNeedsIDs== null || additionalNeedsIDs.Count == 0 ||  
                                            !(AdditionalNeeds.Where(adn => p.ReferenceNumber == adn.FK_Provider_ReferenceNumber).Select(an => an.FK_NeedsList_ID).Except(additionalNeedsIDs).Any())
                                        ) //  *ONLY* records that match the provided list of additionalServiceIDs, no more - no less (aka. Exact Relational Division)

                  select new // anonymous type
                                  {
                                      SettingTown = p.SettingTown,
                                      ProviderTypeCode = ptl.Code,
                                      ProviderName = p.ProviderName,
                                      PublishedAddress = p_po_LeftOuter.PublishedAddressLocation,
                                      Vacancies = p_po_LeftOuter.Vacancies,
                                      VacancyMemo = p_po_LeftOuter.VacancyMemo,
                                      PublishedPhone = p_po_LeftOuter.PublicPhone,
                                      PublishedEmail = p_po_LeftOuter.PublicEmail,
                                      Website = p_po_LeftOuter.Website,
                                      AdditionalNeed = an_nl_LeftOuter.Description,
                                          AdditionalNeedID = (int?)an_nl_LeftOuter.ID,
                                          AdditionalService = ad_svl_LeftOuter.Description,
                                          AdditionalServiceID = (int?)ad_svl_LeftOuter.ID,
                                      CostPerDay = p_po_LeftOuter.CostPerDay,
                                      CostPerHour = p_po_LeftOuter.CostPerHour,
                                      CostPerSession = p_po_LeftOuter.CostPerSession,
                                      Hours = p_po_LeftOuter.Hours,
                                      InspectionOverallJudgement = p_il_LeftOuter.InspectionOVerallJudgement,
                                      ReferenceNumber = p.ReferenceNumber,
                                      ServiceDescription = p_po_LeftOuter.ServiceDescription,
                                      SchoolPickUp = sp_sl_LeftOuter.SchoolName,
                                      Under5 = p_po_LeftOuter.Under5,
                                      Over5 = p_po_LeftOuter.Over5,
                                      PublicTransport = p_po_LeftOuter.PublicTransport,
                                       }).ToList();

Answer 1

错误信息表明您不能在 LINQ to SQL 中使用本地序列，除了 Contains() 函数。根据该建议，尽量避免使用.Except() 并改用.Contains()。您可以替换它：

.Except(localCollection) 

有了这个：

.Where(!localCollection.Contains())

您的案例示例：

(additionalServiceIDs == null || additionalServiceIDs.Count == 0 ||  
    !(AdditionalNeeds.Where(adn => p.ReferenceNumber == adn.FK_Provider_ReferenceNumber)
                     .Select(an => an.FK_ServiceList_ID)
                     .Where(fk => !additionalNeedsIDs.Contains(fk))
                     .Any())
) //  *ONLY* records that match the provided list of additionalServiceIDs, no more - no less (aka. Exact Relational Division)

或通过合并.Where()s 来简化：

(additionalServiceIDs == null || additionalServiceIDs.Count == 0 ||  
    !(AdditionalNeeds.Where(adn => p.ReferenceNumber == adn.FK_Provider_ReferenceNumber 
                                    && !additionalNeedsIDs.Contains(adn.FK_ServiceList_ID))
                     .Select(an => an.FK_ServiceList_ID)
                     .Any())
) //  *ONLY* records that match the provided list of additionalServiceIDs, no more - no less (aka. Exact Relational Division)

Answer 2

在@har07 的帮助下，我完全弄清楚了，过滤器就是这样。

&&
    (additionalServiceIDs == null || additionalServiceIDs.Count == 0 ||
        !(dbo.AdditionalServices.Where(ads => p_ad_LeftOuter.FK_Provider_ReferenceNumber == ads.FK_Provider_ReferenceNumber
                                    && !additionalServiceIDs.Contains(ads.FK_ServiceList_ID)
                                    )
                                    .Select(an => an.FK_ServiceList_ID)
                                    .Any())

        &&
        p_ad_LeftOuter.FK_ServiceList_ID != null
        &&
        dbo.AdditionalServices.Where(ads => p_ad_LeftOuter.FK_Provider_ReferenceNumber == ads.FK_Provider_ReferenceNumber
                                        && additionalServiceIDs.Contains(ads.FK_ServiceList_ID))
                              .Select(an => an.FK_ServiceList_ID)
                              .Distinct()
                              .Count() == additionalServiceIDs.Count
    )
&&
    (additionalNeedsIDs == null || additionalNeedsIDs.Count == 0 ||
        !(dbo.AdditionalNeeds.Where(ads => p_an_LeftOuter.FK_Provider_ReferenceNumber == ads.FK_Provider_ReferenceNumber
                                    && !additionalNeedsIDs.Contains(ads.FK_NeedsList_ID)
                                    )
                                    .Select(an => an.FK_NeedsList_ID)
                                    .Any())

        &&
        p_an_LeftOuter.FK_NeedsList_ID != null
        &&
        dbo.AdditionalNeeds.Where(ads => p_an_LeftOuter.FK_Provider_ReferenceNumber == ads.FK_Provider_ReferenceNumber
                                        && additionalNeedsIDs.Contains(ads.FK_NeedsList_ID))
                              .Select(an => an.FK_NeedsList_ID)
                              .Distinct()
                              .Count() == additionalNeedsIDs.Count
    )