Entity Framework 多个表上的左连接改为创建内连接

Question

我正在尝试创建一个将四个表连接在一起的查询，但保证只有其中一个存在。我以前在 EF 中成功创建过左连接，但从来没有超过一个连接。这是查询：

   var details = (from planInfo in context.PlanInfo
                 join templateRec in context.ProductTemplates
                    on planInfo.TemplateId equals templateRec.TemplateId into templateGroup
                 from template in templateGroup.DefaultIfEmpty()
                 join profileRec in context.CustomerProfiles
                    on planInfo.ProfileId equals profileRec.ProfileId into profileGroup
                 from profile in profileGroup.DefaultIfEmpty()
                 join territoryRec in context.Territories
                    on planInfo.TerritoryId equals territoryRec.TerritoryId into territoryGroup
                 from territory in territoryGroup.DefaultIfEmpty()
                 where planInfo.ActiveStatus
                 && planInfo.PlanId == plan.PlanId
                 select new
                 {
                    PlanId = planInfo.PlanId,
                    TemplateId = planInfo.TemplateId,
                    TemplateGridId = planInfo.TemplateId,
                    ProfileRec = (profile == null ?
                    new
                    {
                       ProfileId = 0,
                       ProfileGridId = 0,
                       Description = string.Empty
                    } :
                    new
                    {
                       ProfileId = profile.ProfileId,
                       ProfileGridId = profile.ProfileId,
                       Description = profile.Description
                    }),
                    ProfileId = (profile == null ? 0 : profile.ProfileId),
                    TerritoryRec = (territory == null ?
                    new
                    {
                       TerritoryId = 0,
                       TerritoryGridId = 0,
                       Description = string.Empty
                    } :
                    new
                    {
                       TerritoryId = territory.TerritoryId,
                       TerritoryGridId = territory.TerritoryId,
                       Description = territory.Description
                    }),
                    TerritoryId = (territory == null ? 0 : territory.TerritoryId),
                    Description = (template == null ? string.Empty: template.Description),
                    TemplateEffectiveDate = planInfo.TemplateEffectiveDate,
                    TemplateExpiryDate = planInfo.TemplateExpiryDate,
                    MinVolume = planInfo.MinVolume,
                    MaxVolume = planInfo.MaxVolume,
                    AccrualPercent = planInfo.AccrualPercent,
                    AccrualPercentNatl = planInfo.AccrualPercentNatl,
                    EffectiveDate = planInfo.EffectiveDate,
                    ExpiryDate = planInfo.ExpiryDate
                 }).ToList();

这是它生成的 SQL。无论我做什么，我总是得到几个 INNER JOIN，然后是 LEFT JOIN，而我想要的是全部 LEFT JOIN。

SELECT 
    [Filter1].[PlanId] AS [PlanId], 
    [Filter1].[TemplateId1] AS [TemplateId], 
    [Filter1].[ProfileId1] AS [ProfileId], 
    [Filter1].[Description1] AS [Description], 
    CASE WHEN ([Extent4].[TerritoryId] IS NULL) THEN CAST(NULL AS int) ELSE 1 END AS [C1], 
    [Extent4].[TerritoryId] AS [TerritoryId], 
    [Extent4].[Description] AS [Description1], 
    CASE WHEN ([Extent4].[TerritoryId] IS NULL) THEN 0 ELSE [Extent4].[TerritoryId] END AS [C2], 
    [Filter1].[Description2] AS [Description2], 
    [Filter1].[TemplateEffectiveDate] AS [TemplateEffectiveDate], 
    [Filter1].[TemplateExpiryDate] AS [TemplateExpiryDate], 
    [Filter1].[MinVolume] AS [MinVolume], 
    [Filter1].[MaxVolume] AS [MaxVolume], 
    [Filter1].[AccrualPercent] AS [AccrualPercent], 
    [Filter1].[AccrualPercentNatl] AS [AccrualPercentNatl], 
    [Filter1].[EffectiveDate] AS [EffectiveDate], 
    [Filter1].[ExpiryDate] AS [ExpiryDate]
    FROM   (SELECT [Extent1].[PlanId] AS [PlanId], [Extent1].[TemplateId] AS [TemplateId1], [Extent1].[TerritoryId] AS [TerritoryId], [Extent1].[TemplateEffectiveDate] AS [TemplateEffectiveDate], [Extent1].[TemplateExpiryDate] AS [TemplateExpiryDate], [Extent1].[MinVolume] AS [MinVolume], [Extent1].[MaxVolume] AS [MaxVolume], [Extent1].[AccrualPercent] AS [AccrualPercent], [Extent1].[AccrualPercentNatl] AS [AccrualPercentNatl], [Extent1].[EffectiveDate] AS [EffectiveDate], [Extent1].[ExpiryDate] AS [ExpiryDate], [Extent2].[Description] AS [Description2], [Extent3].[ProfileId] AS [ProfileId1], [Extent3].[Description] AS [Description1]
        FROM   [dbo].[PlanInfo] AS [Extent1]
        INNER JOIN [dbo].[ProductTemplates] AS [Extent2] ON [Extent1].[TemplateId] = [Extent2].[TemplateId]
        INNER JOIN [dbo].[CustomerProfiles] AS [Extent3] ON [Extent1].[ProfileId] = [Extent3].[ProfileId]
        WHERE [Extent1].[ActiveStatus] = 1 ) AS [Filter1]
    LEFT OUTER JOIN [dbo].[Territories] AS [Extent4] ON [Filter1].[TerritoryId] = [Extent4].[TerritoryId]
    WHERE [Filter1].[PlanId] = '12345'

希望有人能指出我在这里做错了什么。谢谢！

Answer 1

INNER JOINS 代表必需的 n:1 关联。如果您有导航属性，则连接将是对另一个必需实体的引用，而不是集合。 EF 从数据模型中知道 OUTER JOIN 在这里不会产生任何影响，因此它会生成一个 INNER JOIN。

Entity Framework 多个表上的左连接改为创建内连接

Entity Framework left join on multiple tables creates inner join instead

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