当我运行底部看到的 SQL 时,为什么返回:
Msg 1776, Level 16, State 0, Line 2
There are no primary or candidate keys in the referenced table 'pricedex.table_a' that match the referencing column list in the foreign key 'FK_delete_from_parent'.Msg 1750, Level 16, State 0, Line 2
Could not create constraint. See previous errors.
代码:
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
最佳答案
您需要将PRIMARY KEY
添加到table_a
并将PK 列更改为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;
编辑:
Create Foreign Key Relationships
:
A foreign key constraint does not have to be linked only to a primary key constraint in another table; it can also be defined to reference the columns of a UNIQUE constraint in another table.
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
);
请注意,如果列可以为空并且您有 NULL
值,ON DELETE CASCADE
将不会从相应表中删除记录。
关于sql - 如何使用复合键在 SQL Server 中实现参照完整性?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34024777/