Sql表共享多個一對多關係與刪除級聯

我有一個表可以在1 *關係與2個不同的表之一。我目前有它設置哪裏有2個可空的列引用另一個表。但是，這會導致級聯刪除的問題。Sql表共享多個一對多關係與刪除級聯

CREATE TABLE [dbo].[TA] (
    [Id]    INT    IDENTITY (1, 1) NOT NULL, 
    CONSTRAINT [PK_TA] PRIMARY KEY CLUSTERED ([Id] ASC), 
); 

CREATE TABLE [dbo].[TB] (
    [Id]    INT    IDENTITY (1, 1) NOT NULL, 
    [TAId]    INT    NOT NULL, 
    CONSTRAINT [FK_TB_To_TA] FOREIGN KEY ([TAId]) REFERENCES [dbo].[TA] ([Id]) ON DELETE CASCADE, 
    CONSTRAINT [PK_TB] PRIMARY KEY CLUSTERED ([Id] ASC), 
); 

CREATE TABLE [dbo].[TC] (
    [Id]    INT    IDENTITY (1, 1) NOT NULL, 
    [TAId]    INT    NULL, 
    [TBId]    INT    NULL, 
    CONSTRAINT [PK_TC] PRIMARY KEY CLUSTERED ([Id] ASC), 
    CONSTRAINT [FK_TC_To_TA] FOREIGN KEY ([TAId]) REFERENCES [dbo].[TA] ([Id]) ON DELETE CASCADE, 
    CONSTRAINT [FK_TC_To_TB] FOREIGN KEY ([TBId]) REFERENCES [dbo].[TB] ([Id]), -- NOTE: DELETE CASCADE CAUSES A CIRCULAR REFERENCE 
);

本質上，這產生一個嵌套結構等：

TA1 
+ -- TC1, TC2 
+ -- TB1 
     + -- TC3, TC4

甲TC對象應僅是任一TA或TB（不是兩個）的子級。我應該如何去開發這個功能，以便我可以刪除TA行並刪除所有TC和TB引用行？

來源

2015-02-17 jt000

問題在於，基於TC的結構，它可以是TA，TB的孩子，也可以不是。我無法想出一個辦法來實現這一點。這是一個類似問題的答案http://stackoverflow.com/questions/851625/foreign-key-constraint-may-cause-cycles-or-multiple-cascade-paths – Charles380 2015-02-17 22:06:36

這是不幸的...我想我可以刪除除了[TBId]和[TAId] FK列以外，[TBC]和[TAC]創建[TBC]和[TAC]表，其中[TBC]和[TAC]是相同的，但似乎很重複。 – jt000 2015-02-17 22:15:57

爲了解決這個問題，我最終將[TC]分成了多個表格described in a blog for entity framework。這創建了以下表結構：

CREATE TABLE [dbo].[TA] (
    [Id]    INT    IDENTITY (1, 1) NOT NULL, 
    CONSTRAINT [PK_TA] PRIMARY KEY CLUSTERED ([Id] ASC), 
); 

CREATE TABLE [dbo].[TB] (
    [Id]    INT    IDENTITY (1, 1) NOT NULL, 
    [TAId]    INT    NOT NULL, 
    CONSTRAINT [FK_TB_To_TA] FOREIGN KEY ([TAId]) REFERENCES [dbo].[TA] ([Id]) ON DELETE CASCADE, 
    CONSTRAINT [PK_TB] PRIMARY KEY CLUSTERED ([Id] ASC), 
); 

CREATE TABLE [dbo].[TCA] (
    [Id]    INT    IDENTITY (2, 2) NOT NULL, 
    [TAId]    INT    NULL, 
    CONSTRAINT [PK_TCA] PRIMARY KEY CLUSTERED ([Id] ASC), 
    CONSTRAINT [FK_TCA_To_TA] FOREIGN KEY ([TAId]) REFERENCES [dbo].[TA] ([Id]) ON DELETE CASCADE, 
); 


CREATE TABLE [dbo].[TCB] (
    [Id]    INT    IDENTITY (1, 2) NOT NULL, 
    [TBId]    INT    NULL, 
    CONSTRAINT [PK_TCB] PRIMARY KEY CLUSTERED ([Id] ASC), 
    CONSTRAINT [FK_TCB_To_TB] FOREIGN KEY ([TBId]) REFERENCES [dbo].[TB] ([Id]) ON DELETE CASCADE, 
);

我設置的身份甚至\奇數值，以防止碰撞產生兩個表的聯合時（見上面的鏈接）。

來源

2015-02-18 13:22:15 jt000

Sql表共享多個一對多關係與刪除級聯

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