LINQ to SQL不會根據關係生成集合的原因是什麼？

Question

我有兩個實體（e1和e2）之間的關係，e1有e2的集合，但是我在（e2和e3）之間建立了類似的關係，但e2不包含e3的集合，任何原因這會發生？任何我可以發佈，以便更容易弄清楚？

編輯：我只是注意到，e1和e2之間的關係是固體的，e2和e3之間是虛線的，是什麼原因造成的？它有關係嗎？

Answer 1

的FK_Contraints設置了這樣的：。

ALTER TABLE [DBO] [E2] WITH CHECK ADD CONSTRAINT [FK_e2_e1]外鍵（[E1Id]）參考文獻[DBO] [E1]（[ID ]）

ALTER TABLE [DBO]。[E3] WITH CHECK ADD CONSTRAINT [FK_e3_e2]外鍵（[E2Id]）參考文獻[DBO]。[E2]（[ID]）

這就是你請求？

Answer 2

使用此設置，一切正常。

1）LINQ到SQL查詢，2）表DB，3）LINQ到SQL數據模型在VS.NET 2008

1 - LINQ到SQL查詢

DataClasses1DataContext db = new DataClasses1DataContext(); 

var results = from threes in db.tableThrees 
    join twos in db.tableTwos on threes.fk_tableTwo equals twos.id 
    join ones in db.tableOnes on twos.fk_tableOne equals ones.id 
    select new { ones, twos, threes }; 

2 - 數據庫腳本

--Table One 
CREATE TABLE tableOne(
    [id] [int] IDENTITY(1,1) NOT NULL, 
    [value] [nvarchar](50) NULL, 
CONSTRAINT [PK_tableOne] PRIMARY KEY CLUSTERED 
    ([id] ASC) WITH ( 
    PAD_INDEX = OFF, 
    STATISTICS_NORECOMPUTE = OFF, 
    IGNORE_DUP_KEY = OFF, 
    ALLOW_ROW_LOCKS = ON, 
    ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
    ) ON [PRIMARY]; 

--Table Two 
CREATE TABLE tableTwo(
    [id] [int] IDENTITY(1,1) NOT NULL, 
    [value] [nvarchar](50) NULL, 
    [fk_tableOne] [int] NOT NULL, 
CONSTRAINT [PK_tableTwo] PRIMARY KEY CLUSTERED 
    ([id] ASC) WITH (
    PAD_INDEX = OFF, 
    STATISTICS_NORECOMPUTE = OFF, 
    IGNORE_DUP_KEY = OFF, 
    ALLOW_ROW_LOCKS = ON, 
    ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
    ) ON [PRIMARY]; 

ALTER TABLE tableTwo WITH CHECK  
    ADD CONSTRAINT [FK_tableTwo_tableOne] 
    FOREIGN KEY([fk_tableOne]) 
    REFERENCES tableOne ([id]); 

ALTER TABLE tableTwo CHECK CONSTRAINT [FK_tableTwo_tableOne]; 


--Table Three 
CREATE TABLE tableThree(
    [id] [int] IDENTITY(1,1) NOT NULL, 
    [value] [nvarchar](50) NULL, 
    [fk_tableTwo] [int] NOT NULL, 
CONSTRAINT [PK_tableThree] PRIMARY KEY CLUSTERED 
    ([id] ASC) WITH (
    PAD_INDEX = OFF, 
    STATISTICS_NORECOMPUTE = OFF, 
    IGNORE_DUP_KEY = OFF, 
    ALLOW_ROW_LOCKS = ON, 
    ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] 
    ) ON [PRIMARY]; 

ALTER TABLE tableThree WITH CHECK 
    ADD CONSTRAINT [FK_tableThree_tableTwo] 
    FOREIGN KEY([fk_tableTwo]) 
    REFERENCES tableTwo ([id]); 

ALTER TABLE tableThree CHECK CONSTRAINT [FK_tableThree_tableTwo]; 

3 - LINQ to SQL數據模型在Visual Studio

alt text http://i478.photobucket.com/albums/rr148/KyleLanser/ThreeLevelHierarchy.png