MySQL foreign key constraints, cascade delete

Posted by Cudos on Stack Overflow See other posts from Stack Overflow or by Cudos
Published on 2010-05-26T16:32:59Z Indexed on 2010/05/26 20:51 UTC
Read the original article Hit count: 224

Filed under:

mysql

|

foreign-keys

|

innodb

Hello.

I want to use foreign keys to keep the integrity and avoid orphans (I already use innoDB).

How do I make a SQL statment that DELETE ON CASCADE?

Secondly, that using DELETE ON CASCADE. E.g. if I delete a category then it would delete products related to that category even though there are other categories related to those products.

The pivot table "categories_products" creates a many-to-many relationship between the two other tables.

categories
- id (INT)
- name (VARCHAR 255)

products
- id
- name
- price

categories_products
- categories_id
- products_id

© Stack Overflow or respective owner

Related posts about mysql

How to remove MySQL completely with config and library files on ubuntu 12.04 gnome 3.0

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I tried everything till now: sudo apt-get remove mysql-server mysql-client mysql-common sudo apt-get purge mysql-server mysql-client mysql-common sudo apt-get autoremove and even more commands... But whenever I am trying to locate mysql. I get a no. of files related to mysql command: shell>>… >>> More
mysql: Cannot load from mysql.proc. The table is probably corrupted

as seen on Server Fault - Search for 'Server Fault'
Mysql was started: /usr/bin/mysqld_safe --datadir=/srv/mysql/myDB --log-error=/srv/mysql/logs/mysqld-myDB.log --pid-file=/srv/mysql/pids/mysqld-myDB.pid --user=mysql --socket=/srv/mysql/sockets/mysql-myDB.sock --port=3700 but when I'm trying to do something: ERROR 1548 (HY000) at line 1: Cannot… >>> More
Why is there a /etc/init.d/mysql file on this Slackware machine? How could it have gotten there?

as seen on Server Fault - Search for 'Server Fault'
A client of my IT-consulting service owns a web-development shop. He's been having problems with a Slackware 12.0 server running MySQL 5.0.67. The machine was set up by the client's sysadmin, who left on bad terms. My client no longer employs a sysadmin. As far as I can tell, the only copy of MySQL… >>> More
mysql: Bind on unix socket: Permission denied

as seen on Server Fault - Search for 'Server Fault'
Can't start mysql with: sudo /usr/bin/mysqld_safe --datadir=/srv/mysql/myDB --log-error=/srv/mysql/logs/mysqld-myDB.log --pid-file=/srv/mysql/pids/mysqld-myDB.pid --user=mysql --socket=/srv/mysql/sockets/mysql-myDB.sock --port=3700 120222 13:40:48 mysqld_safe Starting mysqld daemon with databases… >>> More
MySQL – Learning MySQL Online in 6 Hours – MySQL Fundamentals in 320 Minutes

as seen on SQL Authority - Search for 'SQL Authority'
MySQL is one of the most popular database language and I have been recently working with it a lot. Data have no barrier and every database have their own place. I have been working with MySQL for quite a while and just like SQL Server, I often find lots of people asking me if I have a tutorial which… >>> More

Related posts about foreign-keys

Foreign keys in django admin list display

as seen on Stack Overflow - Search for 'Stack Overflow'
If a django model contains a foreign key field, and if that field is shown in list mode, then it shows up as text, instead of displaying a link to the foreign object. Is it possible to automatically display all foreign keys as links instead of flat text? (of course it is possible to do that on a… >>> More
Multiple foreign keys in one table to 1 other table in mysql

as seen on Stack Overflow - Search for 'Stack Overflow'
Hey guys, I got 2 tables in my database: user and call. User exists of 3 fields: id, name, number and call : id, 'source', 'destination', 'referred', date. I need to monitor calls in my app. The 3 ' ' fields above are actually userid numbers. now i'm wondering, can i make those 3 field foreign… >>> More
Create automatically table that is composed by its primery key and 2 other foreign keys

as seen on Stack Overflow - Search for 'Stack Overflow'
I have table A with a primary id, a table B with a primary key id also and another table C with a primary key id and rows Aid and Bid where Aid and Bid are foreign keys of C and the primary keys of A and B respectively. One way of populating these DB would be populating table A, table B and table… >>> More
Foreign keys with Rails' ActiveRecord::Migration?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, I'm new to Ruby on Rails (I know Ruby just decently though) and looking at the Migration tools, it sounds really awesome. Database schemas can finally (easily) go in source control. Now my problem with it. When using Postgres as the database, it does not setup foreign keys. I would like the… >>> More
Working with foreigh keys - cannot insert

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi everyone! Doing my first tryouts with foreign keys in a mySQL database and are trying to do a insert, that fails for this reason: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails Does this mean that foreign keys restrict INSERTS as well as… >>> More