本文介绍了没有主键的外键引用的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有以下两张表.
CREATE TABLE parent
( c1 INTEGER );
CREATE TABLE child
(
c1 INTEGER,
c2 INTEGER,
c3 INTEGER,
CONSTRAINT fk_c3 FOREIGN KEY(c3) REFERENCES parent(c1)
);
您一定已经注意到列 c1 不是父表中的主键.有没有办法在子表中引用它而不将 c1 作为主键?
You must have noticed that column c1 is NOT a primary key in Parent table.
Is there any way to refer it in Child table without making c1 as a primary key?
推荐答案
有没有办法在子表中引用它而不将'c1'作为主键?
Is there any way to refer it in Child table without making 'c1' as a primary key?
是的.外键只需要引用唯一约束 - 它不必是主键.您可以在该列上创建一个独特的约束.
Yes. A foreign key needs only to refer to a unique constraint - it does not have to be a primary key. You could create a unique contraint on that column.
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