Btw, I made some tests with "on delete cascade" in mysql and
discovered an issue: the cascade delete doesn't fire a trigger defined
on the deleted row. Even this dB engine (innodb) doesn't implement the
cascade delete in a consistent way.
--
Guillaume
Envoyé de mon iPhone
Le 31 mars 2010 à 17:39, Bill Karwin <[email protected]> a écrit :
On Mar 31, 2010, at 8:24 AM, Jared Williams wrote:
I don't think it is possible to implement a robust cascading delete
in
an application without transaction support. (eg MyISAM)
You need a transaction to ensure either all the delete statements
run,
or none of them.
Yes, this is correct -- but you have to roll back the transaction
manually, and it's up to you to detect an unsatisfied reference if
you don't use foreign key constraints.
If you use database-enforced constraints, you don't even have to use
explicit transactions. The database constraints ensure that all
cascading operations succeed, or else they all fail.
For those people who insist that they can make their database stay
consistent (that is, all references are satisfied at all times) by
enforcing it in their PHP space, I'd suggest you run some quality
control SQL scripts to check for orphaned child rows.
Regards,
Bill Karwin
