Re: onDelete cascade after table has been created

On Saturday, February 20, 2016 at 8:48:21 PM UTC+5:30, Tony Mountifield wrote:
> In article <afdf9d11-31be-4173-ac9c-1adc22f2fef9_at_googlegroups.com>,
> <apoorv.kanungo_at_gmail.com> wrote:
> > Hello I know we can use cascading while creating table but After I created table and there are bunch of data in it how
> > would I do ondelete cascade.
> >
> > I have a user table and a article table with one to many relationship and I have a foreign key user_id in article which
> > refrences id in user table when I ran this query
> >
> > ALTER TABLE `article`
> > FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE CASCADE;
> >
> > Now i Have foreign key but when I delete an entry in user table the corresponding entry in article does not get deleted.
>
> First thing would be to check the table definitions:
>
> SHOW CREATE TABLE `article`;
> SHOW CREATE TABLE `user`;
>
> and make sure the foreign key definition really exists.
>
> Also check what the ENGINE is for those tables. If the engine is MyISAM,
> then foreign key definitions are accepted but not acted upon. You need
> the ENGINE to be InnoDB:
>
> ALTER TABLE `article` ENGINE=InnoDB;
> ALTER TABLE `user` ENGINE=InnoDB;
>
> Cheers
> Tony
> --
> Tony Mountifield
> Work: tony_at_softins.co.uk - http://www.softins.co.uk
> Play: tony_at_mountifield.org - http://tony.mountifield.org

Hello Foreign Key does exist I can see in the structure tab the little key thing beside user_id I changed storage engine to innodb If I do describe article under user_id key has value mul under indexes it has following value
user_id BTREE No No user_id 1 A No
Even If I HAVE a user with an id=4 and artcle in article table with user_id=4 if I delete user the entry in article table does not get deleted.   Received on Mon Feb 22 2016 - 09:44:01 CET