mysql - 添加带有更新级联的外键

Question

假设我有 2 张 table

用户

+----+--------+
| id | status |
+----+--------+
|  1 | A      |
|  2 | A      |
+----+--------+

文章

+----+-----+--------+
| id | uid | status |
+----+-----+--------+
|  1 |   1 | A      |
|  2 |   2 | A      |
|  3 |   2 | A      |
|  4 |   2 | A      |
|  5 |   1 | A      |
|  6 |   2 | A      |
|  7 |   2 | A      |
|  8 |   1 | A      |
|  9 |   2 | A      |
| 10 |   2 | A      |
+----+-----+--------+

如果运行此查询，如何添加外键:

UPDATE user SET status='B' WHERE id=1 OR id=2;

结果将是:

用户

+----+--------+
| id | status |
+----+--------+
|  1 | B      |
|  2 | B      |
+----+--------+

文章

+----+-----+--------+
| id | uid | status |
+----+-----+--------+
|  1 |   1 | B      |
|  2 |   2 | B      |
|  3 |   2 | B      |
|  4 |   2 | B      |
|  5 |   1 | B      |
|  6 |   2 | B      |
|  7 |   2 | B      |
|  8 |   1 | B      |
|  9 |   2 | B      |
| 10 |   2 | B      |
+----+-----+--------+

或者换句话说，如果我更新列user.status，MySQL将自动使用相应的值更新列article.status。

如何创建这个外键？

Answer 1

该工作不是外键可以完成的。使用更新触发器，但为了更好的数据库兼容性，最好对您的代码执行此操作。

触发代码:

CREATE TRIGGER SetArticleStatus AFTER UPDATE ON user 
FOR EACH ROW 
BEGIN 
UPDATE `article` 
   SET status = NEW.status 
 WHERE uid = NEW.id
END