Question

我有以下linq查询

var result = from myTypes in context.MyTypes
where
  ((myTypes .Prop1== "Test" ? 1 : 0) + 
  (myTypes .Prop2 == "Tester2" ? 1 : 0) + 
  (myTypes .Prop3 == "624642624000000000" ? 1 : 0) + 
  (myTypes .Prop4 == "TS166TH" ? 1 : 0) + 
  (myTypes .Prop5 == "1 Test Lane" ? 1 : 0)) >= 4
  select new {
  myTypes .Prop1,
  myTypes .Prop2,
  myTypes .Prop3,
  myTypes .Prop4,
  myTypes .Prop5,
  myTypes .OtherProp,
  myTypes .OtherTypeId
};

result.ToList();

这导致以下预期的SQL，这是我想要实现的

SELECT 
[Extent1].[Prop1] AS [Prop1], 
[Extent1].[Prop2] AS [Prop2], 
[Extent1].[Prop3] AS [Prop3], 
[Extent1].[Prop4] AS [Prop4], 
[Extent1].[Prop5] AS [Prop5], 
[Extent1].[OtherProp] AS [OtherProp], 
[Extent1].[OtherTypeId] AS [OtherTypeId],

FROM [dbo].[MyType] AS [Extent1]
WHERE ((CASE WHEN ('Test' = [Extent1].[Prop1]) THEN 1 ELSE 0 END) + (CASE WHEN ('Tester2' = [Extent1].[Prop2]) THEN 1 ELSE 0 END) + (CASE WHEN ('624642624000000000' = [Extent1].[Prop3]) THEN 1 ELSE 0 END) + (CASE WHEN ('TS166TH' = [Extent1].[Prop4]) THEN 1 ELSE 0 END) + (CASE WHEN ('1 Test Lane' = [Extent1].[Prop5]) THEN 1 ELSE 0 END)) >= 4

但是我想返回MyType而不是匿名类型，所以我写了以下内容

var result = from myTypes in context.MyTypes
where
  ((myTypes .Prop1== "Test" ? 1 : 0) + 
  (myTypes .Prop2 == "Tester2" ? 1 : 0) + 
  (myTypes .Prop3 == "624642624000000000" ? 1 : 0) + 
  (myTypes .Prop4 == "TS166TH" ? 1 : 0) + 
  (myTypes .Prop5 == "1 Test Lane" ? 1 : 0)) >= 4
  select myTypes; 

result.ToList();

我希望生成相同的查询但返回我的类型。相反，我发现它执行一个大规模的递归查询（基本上查询表中的每个记录）如下所示。

SELECT 
[Extent1].[Prop1] AS [Prop1], 
[Extent1].[Prop2] AS [Prop2], 
[Extent1].[Prop3] AS [Prop3], 
[Extent1].[Prop4] AS [Prop4], 
[Extent1].[Prop5] AS [Prop5],
[Extent1].[OtherProp] AS [OtherProp],
[Extent1].[OtherTypeId] AS [OtherTypeId],
FROM [dbo].[MyType] AS [Extent1]
WHERE ((CASE WHEN ('Test' = [Extent1].[Prop1]) THEN 1 ELSE 0 END) + (CASE WHEN ('Tester2' = [Extent1].[Prop2]) THEN 1 ELSE 0 END) + (CASE WHEN ('624642624000000000' = [Extent1].[Prop3]) THEN 1 ELSE 0 END) + (CASE WHEN ('TS166TH' = [Extent1].[Prop4]) THEN 1 ELSE 0 END) + (CASE WHEN ('1 Test Lane' = [Extent1].[Prop5]) THEN 1 ELSE 0 END)) >= 4
GO

SELECT 
[Extent1].[OtherTypeId] AS [OtherTypeId], 
[Extent1].[OtherTypeProp] AS [OtherTypeProp], 
FROM [dbo].[OtherTypes] AS [Extent1]
GO

-- Region Parameters
DECLARE EntityKeyValue1 BigInt = 1
-- EndRegion
SELECT 
[Extent1].[Prop1] AS [Prop1], 
[Extent1].[Prop3] AS [Prop2], 
[Extent1].[Prop3] AS [Prop3], 
[Extent1].[Prop4] AS [Prop4], 
[Extent1].[Prop5] AS [Prop5], 
[Extent1].[OtherProp] AS [OtherProp], 

WHERE [Extent1].[OtherTypeId] = @EntityKeyValue1
GO

-- Region Parameters
DECLARE EntityKeyValue1 BigInt = 2
-- EndRegion
SELECT 
[Extent1].[Prop1] AS [Prop1], 
[Extent1].[Prop3] AS [Prop2], 
[Extent1].[Prop3] AS [Prop3], 
[Extent1].[Prop4] AS [Prop4], 
[Extent1].[Prop5] AS [Prop5], 
[Extent1].[OtherProp] AS [OtherProp], 

WHERE [Extent1].[OtherTypeId] = @EntityKeyValue1
GO

看起来它正在为每条记录获取所有fk类型并忽略where子句？

任何人都可以解释我在这里做错了什么，为什么两个生成的查询不同？

Answer 1

好的，这很令人尴尬。

我使用LinqPad测试查询，并在Dump()结果上调用了ToList()。 Dump（）枚举通过db中所有相关记录引起循环枚举的所有属性。对匿名类型的转储只列出所有属性，没有实体导航属性导致枚举。

将来在实体上使用LinqPad的Dump（）方法的所有注释。向所有人道歉，浪费时间。男生错误。

具有匿名类型的linq案例查询行为

1 个答案: