[英]How do I do referential integrity in SQL Server with a compound key?
當我運行底部顯示的SQL時,為什么返回:
消息1776,級別16,狀態0,第2行
在引用表“ priceex.table_a”中沒有與外鍵“ FK_delete_from_parent”中的引用列列表匹配的主鍵或候選鍵。消息1750,級別16,狀態0,第2行
無法創建約束。 請參閱先前的錯誤。
碼:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE table_a
(
[column_1] [int] NULL,
[column_2] [int] NULL
)
CREATE TABLE table_b
(
[column_1] [int] NULL,
[column_2] [int] NULL
)
GO
CREATE NONCLUSTERED INDEX IX_app ON table_a (column_1, column_2)
GO
CREATE NONCLUSTERED INDEX IX_app ON table_b (column_1, column_2)
GO
SET ANSI_PADDING OFF
GO
ALTER TABLE table_b WITH CHECK
ADD CONSTRAINT FK_delete_from_parent
FOREIGN KEY (column_1, column_2) REFERENCES table_a (column_1, column_2)
ON DELETE CASCADE
GO
您需要將PRIMARY KEY
添加到table_a
並將PK的列更改為NOT NULL
:
CREATE TABLE table_a (
[column_1] [int] NOT NULL,
[column_2] [int] NOT NULL,
PRIMARY KEY(column_1, column_2) -- compound primary key
);
CREATE TABLE table_b (
[column_pk] [int] NOT NULL PRIMARY KEY, -- you probably want different pk
[column_1] [int] NULL,
[column_2] [int] NULL
);
-- adding foreign key constraint
ALTER TABLE table_b WITH CHECK
ADD CONSTRAINT FK_delete_from_parent FOREIGN KEY (column_1, column_2)
REFERENCES table_a (column_1, column_2) ON DELETE CASCADE;
編輯:
Create Foreign Key Relationships
:
外鍵約束不必僅鏈接到另一個表中的主鍵約束。 還可以定義它引用另一個表中UNIQUE約束的列。
CREATE TABLE table_a (
[column_1] [int] NOT NULL, -- with UNIQUE column can be nullable
[column_2] [int] NOT NULL,
UNIQUE(column_1, column_2)
-- anyway this table should have PK
);
請注意,如果列是可空的並且您具有NULL
值,則ON DELETE CASCADE
不會從相應表中刪除記錄。
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