MySQL添加外键错误1215

Question

我知道以前有人问过这样的问题。我确保它们具有相同的数据类型并检查了我的语法，但我仍然收到错误:

 ALTER TABLE meetings ADD FOREIGN KEY (ownerName) REFERENCES employees(name);

ERROR 1215 (HY000): Cannot add foreign key constraint

mysql> desc `meetings`;
    +-----------+-------------+------+-----+---------+----------------+
    | Field     | Type        | Null | Key | Default | Extra          |
    +-----------+-------------+------+-----+---------+----------------+
    | id        | int(11)     | NO   | PRI | NULL    | auto_increment |
    | room      | int(6)      | NO   |     | NULL    |                |
    | ownerName | varchar(30) | NO   |     | NULL    |                |
    | ownerID   | varchar(30) | NO   |     | NULL    |                |
    +-----------+-------------+------+-----+---------+----------------+
    4 rows in set (0.00 sec)

    mysql> desc `employees`;
    +----------+--------------+------+-----+---------+-------+
    | Field    | Type         | Null | Key | Default | Extra |
    +----------+--------------+------+-----+---------+-------+
    | name     | varchar(30)  | NO   |     | NULL    |       |
    | username | varchar(30)  | NO   | PRI | NULL    |       |
    | pswd     | varchar(255) | YES  |     | NULL    |       |
    +----------+--------------+------+-----+---------+-------+

我做错了什么？

Answer 1

name 不是 employees 表中的主键，所以 .. 尝试使用 username

ALTER TABLE meetings ADD FOREIGN KEY (ownerName) REFERENCES employees(username);

或按照 DanielE 的建议，或者您可以使用 name 列，但此列需要一个 UNIQUE 索引