Hi,
This is an example:
ALTER TABLE cart ADD CONSTRAINT fk_cart_customers FOREIGN KEY (custid)
REFERENCES customers (custid)
ON DELETE CASCADE
ON UPDATE NO ACTION;
(take from the GUI tool Database Workbench, avoids having to know the syntax
;) )
With regards,
Martijn Tonies
Upscene Productions
http://www.upscene.com
Download Database Workbench for Oracle, MS SQL Server, Sybase SQL
Anywhere, MySQL, InterBase, NexusDB and Firebird!
-----Original Message-----
From: thufir
Sent: Monday, November 17, 2014 10:42 AM
To: mysql@lists.mysql.com
Subject: alter table for foreign key
Looking at the docs:
http://dev.mysql.com/doc/refman/5.6/en/create-table-foreign-keys.html
how do I alter the child table, links, so that it has a foreign key with
the parent table, feeds?
The feed_id field in links should, in fact, be constrained by the foreign
key of feeds with a RESTRICT reference option.
mysql>
mysql> show tables;
+---------------------------+
| Tables_in_rome_aggregator |
+---------------------------+
| feeds |
| links |
| pages |
+---------------------------+
3 rows in set (0.00 sec)
mysql>
mysql> describe feeds;
+----------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+----------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| created | datetime | NO | | NULL | |
| accessed | varchar(45) | NO | | NULL | |
| url | varchar(767) | NO | UNI | NULL | |
| status | int(11) | NO | | 0 | |
+----------+--------------+------+-----+---------+----------------+
5 rows in set (0.05 sec)
mysql>
mysql> describe links;
+---------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| created | datetime | NO | | NULL | |
| feed_id | int(11) | NO | | 0 | |
| link | varchar(767) | NO | UNI | NULL | |
| status | int(11) | NO | | 0 | |
+---------+--------------+------+-----+---------+----------------+
5 rows in set (0.00 sec)
mysql>
While I know that I should alter the table, I don't know the syntax to
establish the foreign key constraint.
thanks,
Thufir
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe: http://lists.mysql.com/mysql
