我在使用EF4时遇到了麻烦,使用类型对应每个表(TPT)继承构建高效查询困难。
我有一个名为Episode的实体,每个剧集都可以有多个事件。有几种不同类型的事件都是从称为Event的基础实体派生而来的。我想过滤掉不包含某种类型事件的所有剧集。Episode有一个导航属性,它是其所有事件的集合(即基本Event类型的集合)。
我尝试过:
from episode in context.EpisodeSet
where episode.Events.OfType<DerivedEvent>().Count() == 0
select episode
并且
from episode in context.EpisodeSet
where episode.Events.Where(p => p is DerivedEvent).Count() == 0
select episode
这两种方法都会生成一个典型的长SQL扩展,查询每个事件类型表。
难道没有一种用LINQ表达这个查询的方式,只涉及到结果SQL中的剧集和派生事件表之间的连接吗?
编辑: 响应ProfessorX,在此处生成了SQL(基本上只是跨所有事件表的典型大联合)
SELECT
[Extent1].[Id] AS [Id],
[Extent1].[TypeId] AS [TypeId],
[Extent1].[PatientId] AS [PatientId],
[Extent1].[CentreId] AS [CentreId],
[Extent1].[CreatedOn] AS [CreatedOn],
[Extent1].[UpdatedOn] AS [UpdatedOn],
[Extent1].[CreatedBy] AS [CreatedBy],
[Extent1].[UpdatedBy] AS [UpdatedBy]
FROM [dbo].[Episode] AS [Extent1]
WHERE EXISTS (SELECT
1 AS [C1]
FROM [dbo].[Event] AS [Extent2]
LEFT OUTER JOIN (SELECT
[Extent3].[Id] AS [Id],
cast(1 as bit) AS [C1]
FROM [dbo].[InvasiveDischargableEvent] AS [Extent3] ) AS [Project1] ON [Extent2].[Id] = [Project1].[Id]
LEFT OUTER JOIN (SELECT
[UnionAll4].[C1] AS [C1],
[UnionAll4].[C2] AS [C2],
[UnionAll4].[C3] AS [C3],
[UnionAll4].[C4] AS [C4],
[UnionAll4].[C5] AS [C5],
[UnionAll4].[C6] AS [C6],
[UnionAll4].[C7] AS [C7]
FROM (SELECT
[UnionAll3].[C1] AS [C1],
[UnionAll3].[C2] AS [C2],
[UnionAll3].[C3] AS [C3],
[UnionAll3].[C4] AS [C4],
[UnionAll3].[C5] AS [C5],
[UnionAll3].[C6] AS [C6],
[UnionAll3].[C7] AS [C7]
FROM (SELECT
[UnionAll2].[C1] AS [C1],
[UnionAll2].[C2] AS [C2],
[UnionAll2].[C3] AS [C3],
[UnionAll2].[C4] AS [C4],
[UnionAll2].[C5] AS [C5],
[UnionAll2].[C6] AS [C6],
[UnionAll2].[C7] AS [C7]
FROM (SELECT
[UnionAll1].[Id] AS [C1],
[UnionAll1].[C1] AS [C2],
[UnionAll1].[C2] AS [C3],
[UnionAll1].[C3] AS [C4],
[UnionAll1].[C4] AS [C5],
[UnionAll1].[C5] AS [C6],
[UnionAll1].[C6] AS [C7]
FROM (SELECT
[Extent4].[Id] AS [Id],
cast(0 as bit) AS [C1],
cast(1 as bit) AS [C2],
cast(0 as bit) AS [C3],
cast(0 as bit) AS [C4],
cast(0 as bit) AS [C5],
cast(0 as bit) AS [C6]
FROM [dbo].[InvasivePSQ10Event] AS [Extent4]
UNION ALL
SELECT
[Extent5].[Id] AS [Id],
cast(0 as bit) AS [C1],
cast(0 as bit) AS [C2],
cast(0 as bit) AS [C3],
cast(0 as bit) AS [C4],
cast(0 as bit) AS [C5],
cast(1 as bit) AS [C6]
FROM [dbo].[InvasivePostTreatmentEvent] AS [Extent5]) AS [UnionAll1]
UNION ALL
SELECT
[Extent6].[Id] AS [Id],
cast(0 as bit) AS [C1],
cast(0 as bit) AS [C2],
cast(1 as bit) AS [C3],
cast(0 as bit) AS [C4],
cast(0 as bit) AS [C5],
cast(0 as bit) AS [C6]
FROM [dbo].[InvasiveTreatmentEvent] AS [Extent6]) AS [UnionAll2]
UNION ALL
SELECT
[Extent7].[Id] AS [Id],
cast(0 as bit) AS [C1],
cast(0 as bit) AS [C2],
cast(0 as bit) AS [C3],
cast(0 as bit) AS [C4],
cast(1 as bit) AS [C5],
cast(0 as bit) AS [C6]
FROM [dbo].[InvasiveConsultationEvent] AS [Extent7]) AS [UnionAll3]
UNION ALL
SELECT
[Extent8].[Id] AS [Id],
cast(1 as bit) AS [C1],
cast(0 as bit) AS [C2],
cast(0 as bit) AS [C3],
cast(0 as bit) AS [C4],
cast(0 as bit) AS [C5],
cast(0 as bit) AS [C6]
FROM [dbo].[InvasiveMOXFQEvent] AS [Extent8]) AS [UnionAll4]
UNION ALL
SELECT
[Extent9].[Id] AS [Id],
cast(0 as bit) AS [C1],
cast(0 as bit) AS [C2],
cast(0 as bit) AS [C3],
cast(1 as bit) AS [C4],
cast(0 as bit) AS [C5],
cast(0 as bit) AS [C6]
FROM [dbo].[InvasiveReferralEvent] AS [Extent9]) AS [UnionAll5] ON [Extent2].[Id] = [UnionAll5].[C1]
WHERE ([Extent1].[Id] = [Extent2].[EpisodeId]) AND (CASE WHEN (( NOT (([UnionAll5].[C2] = 1) AND ([UnionAll5].[C2] IS NOT NULL))) AND ( NOT (([UnionAll5].[C3] = 1) AND ([UnionAll5].[C3] IS NOT NULL))) AND ( NOT (([UnionAll5].[C4] = 1) AND ([UnionAll5].[C4] IS NOT NULL))) AND ( NOT (([Project1].[C1] = 1) AND ([Project1].[C1] IS NOT NULL))) AND ( NOT (([UnionAll5].[C5] = 1) AND ([UnionAll5].[C5] IS NOT NULL)))) THEN '2X' WHEN (([UnionAll5].[C5] = 1) AND ([UnionAll5].[C5] IS NOT NULL)) THEN '2X0X' WHEN (([Project1].[C1] = 1) AND ([Project1].[C1] IS NOT NULL) AND ( NOT (([UnionAll5].[C6] = 1) AND ([UnionAll5].[C6] IS NOT NULL))) AND ( NOT (([UnionAll5].[C7] = 1) AND ([UnionAll5].[C7] IS NOT NULL)))) THEN '2X1X' WHEN (([UnionAll5].[C4] = 1) AND ([UnionAll5].[C4] IS NOT NULL)) THEN '2X2X' WHEN (([UnionAll5].[C2] = 1) AND ([UnionAll5].[C2] IS NOT NULL)) THEN '2X3X' WHEN (([UnionAll5].[C6] = 1) AND ([UnionAll5].[C6] IS NOT NULL)) THEN '2X1X0X' WHEN (([UnionAll5].[C7] = 1) AND ([UnionAll5].[C7] IS NOT NULL)) THEN '2X1X1X' ELSE '2X4X' END LIKE '2X4X%')
)