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如何为我的数据创建交叉引用表/查询?

cross-reference database-design sql

Dillie-O · 技术社区 · 17 年前

我的数据库中有两个简单的表。包含卡的Id、名称和文本的“卡”表,以及包含卡的Id和详细说明卡的规则的文本的“规则”表。

我想做的是能够创建一个交叉引用表(或过程,如果它足够有效的话),这样当我提交一个卡的查询时,我可以通过Id找到直接引用卡的所有规则记录,并获得文本中引用卡名的所有规则记录。

最好的方法是什么?我的环境是SQL2005,但是任何一种“DB不可知”的解决方案在这里都被广泛接受。

2 回复 | 直到 17 年前

Tom H zenazn 17 年前

这似乎是一个相当简单和常见的关系问题,可以通过交叉引用表来解决。例如:

CREATE TABLE dbo.Cards (
    id        INT            NOT NULL,
    name      VARCHAR(50)    NOT NULL,
    card_text VARCHAR(4000)  NOT NULL,
    CONSTRAINT PK_Cards PRIMARY KEY CLUSTERED (id)
)
GO
CREATE TABLE dbo.Card_Rulings (
    card_id        INT            NOT NULL,
    ruling_number  INT            NOT NULL,
    ruling_text    VARCHAR(4000)  NOT NULL,
    CONSTRAINT PK_Card_Rulings PRIMARY KEY CLUSTERED (card_id, ruling_number)
)
GO
CREATE TABLE dbo.Card_Ruling_Referenced_Cards (
    parent_card_id    INT    NOT NULL,
    ruling_number     INT    NOT NULL,
    child_card_id     INT    NOT NULL,
    CONSTRAINT PK_Card_Ruling_Referenced_Cards PRIMARY KEY CLUSTERED (parent_card_id, ruling_number, child_card_id)
)
GO
ALTER TABLE dbo.Card_Rulings
ADD CONSTRAINT FK_CardRulings_Cards FOREIGN KEY (card_id) REFERENCES dbo.Cards(id)
GO
ALTER TABLE dbo.Card_Ruling_Referenced_Cards
ADD CONSTRAINT FK_CardRulingReferencedCards_CardRulings FOREIGN KEY (parent_card_id, ruling_number) REFERENCES dbo.Card_Rulings (card_id, ruling_number)
GO
ALTER TABLE dbo.Card_Ruling_Referenced_Cards
ADD CONSTRAINT FK_CardRulingReferencedCards_Cards FOREIGN KEY (child_card_id) REFERENCES dbo.Cards(id)
GO

要获取卡的所有卡规则,请执行以下操作:

SELECT *
FROM dbo.Cards C
INNER JOIN dbo.Card_Rulings CR ON CR.card_id = C.id
WHERE C.id = @card_id

SELECT C.*
FROM dbo.Card_Rulings CR
INNER JOIN dbo.Card_Ruling_Referenced_Cards CRRC ON CRRC.parent_card_id = CR.card_id
INNER JOIN dbo.Cards C ON C.id = CRRC.child_card_id
WHERE CR.card_id = @card_id

您的前端将负责维护引用。这可能是可取的,因为它避免了有人在规则文本中忘记在卡片名称周围加引号等问题。

George Mastros 17 年前

我建议您创建另一个存储引用的表。然后,创建一个维护此表的insert和update触发器。这样,您将有一个更快的查询来返回您正在查找的数据。

Declare @Card Table(Id Int, Name VarChar(20), CardText VarChar(8000))

Declare @Ruling Table(CardId Int, CardRuling VarChar(8000))

Insert Into @Card Values(1, 'Card 1', 'This is the card ID = 1')
Insert Into @Card Values(2, 'Card 2', 'This is the card id = 2.')
Insert Into @Card Values(3, 'Card 3', 'This is the card id = 3.')

Insert Into @Ruling Values(1, 'This is the ruling for 1 which references "2"')
Insert Into @Ruling Values(2, 'This is the ruling for 2 which references nothing')
Insert Into @Ruling Values(3, 'This is the ruling for 3 which references "1" and "2"')

Declare @CardId Int
Set @CardId = 1

Select  * 
From    @Card As Card
        Inner Join @Ruling As Ruling
            On Card.Id = Ruling.CardId
        Left Join @Card As CardReferences
            On Ruling.CardRuling Like '%"' + Convert(VarChar(10), CardReferences.Id) + '"%'

我建议使用另一个表的原因是,您可能会对该查询的性能感到失望,尤其是对于大型表。