MySql 查询浏览器：alter table for foreign key

Question

如何使 message_id 成为外键，以便 cmets 和消息之间是一对多的？ （一条消息可以有多个 cmets。）

mysql> use nntp;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
+----------------+
| Tables_in_nntp |
+----------------+
| comments       |
| messages       |
+----------------+
2 rows in set (0.00 sec)

mysql> describe comments;
+------------+---------+------+-----+---------+-------+
| Field      | Type    | Null | Key | Default | Extra |
+------------+---------+------+-----+---------+-------+
| id         | int(11) | NO   | PRI | NULL    |       |
| message_id | int(11) | NO   |     | NULL    |       |
| comment    | text    | NO   |     | NULL    |       |
| stamp      | date    | NO   |     | NULL    |       |
+------------+---------+------+-----+---------+-------+
4 rows in set (0.00 sec)

mysql> describe messages;
+-----------+---------+------+-----+---------+-------+
| Field     | Type    | Null | Key | Default | Extra |
+-----------+---------+------+-----+---------+-------+
| id        | int(11) | NO   | PRI | NULL    |       |
| newsgroup | text    | NO   |     | NULL    |       |
| subject   | text    | NO   |     | NULL    |       |
| content   | text    | NO   |     | NULL    |       |
| number    | text    | NO   |     | NULL    |       |
+-----------+---------+------+-----+---------+-------+
5 rows in set (0.00 sec)

mysql> quit
Bye
thufir@dur:~/NetBeansProjects/USENET$ 

我用的是MySql查询浏览器看看：

虽然我可以从查询浏览器或命令行输入 SQL，但我对它不是很熟悉。如果可能，我更愿意为此使用 GUI 查询浏览器。

Answer 1

应该做的伎俩：

ALTER TABLE comments ADD FOREIGN KEY (message_id) REFERENCES messages(id);

从阅读MySQL documentation 可以看出。