[英]MySql query browser: alter table for foreign key
how do I make message_id a foreign key so that it's one-to-many between comments and messages? 如何使message_id成为外键,以便它在注释和消息之间是一对多的? (One message can have many comments.) (一条消息可以有很多评论。)
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$
I'm using the MySql query browser and see: 我正在使用MySql查询浏览器并查看:
While I can enter SQL either from the query browser or command line, I'm not very familiar with it. 虽然我可以从查询浏览器或命令行输入SQL,但我对它并不熟悉。 I would prefer to use the GUI query browser, if possible, for this. 如果可能的话,我更愿意使用GUI查询浏览器。
Should do the trick: 应该做的诀窍:
ALTER TABLE comments ADD FOREIGN KEY (message_id) REFERENCES messages(id);
As one could tell from reading the MySQL documentation . 从阅读MySQL文档可以看出。
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