><snip>
>>I think it's a good idea in any case because DB support does not give you
>>the control over this behaviour. You can only define it when you create
the
>>table. If you, however, use programmatic implementation you explicitly
>>specify whether you want to delete the record only if it has no children
>>or delete any children if there are. An example would be some financial
app
>>where a Clerk would only be able to delete an empty bill (created by
>>mistake) while a Supervisor would be able to delete any bill whether empty
>>or not (do not critisize the example).
>
>In your example, before a Clerk is allowed to delete a bill a check will be
run if
>the bill is empty before the action is performed (no cascading necessary
here).
>If a Supervisor deletes the bill you want all items on the bill to be
deleted as
>well - ON DELETE CASCADE.
I asked not to critisize the example! ;-)
>It actually reduces programmer error because a programmer does not have to
>remember do call doDeleteWithCascade instead of doDelete. Without ON DELETE
>CASCADE you need to make sure that your action is part of an atomic
transaction
>(another place for programmer error) whereas with it you needn't worry.
Both are
>reasons for you to be more certain of the your database integrity. Less
code; Less
>bugs :-)
I think this way _encourages_ programmer error because programmer who did
not mean to do a cascade delete (such as in clerk's case) he may fire this
method without checking if there are child records or with that check
performed improperly.
Looks like I have A proposal:
---
Add method doDelete(Criteria crit, DeleteMode deleteMode)
where deleteMode can take values of CASCADE, RESTRICT or DONTCARE
for each foreign key referencing this table:
{
if (FK is defined with ON DELETE CASCADE)
or ((ON DELETE is not specified for FK) and (deleteMode == CASCADE))
{
if (DB supports cascade DELETEs) and (FK is defined with ON DELETE
CASCADE)
{
do nothing - DB will do it for you
}
else
{
delete dependent records
}
}
else if (FK is defined with ON DELETE RESTRICT)
or ((ON DELETE is not specified for FK) and (deleteMode ==
RESTRICT))
{
if (DB supports Ref Integrity)
{
do nothing -- DB will take care of it
}
else
{
check if there are dependent records and throw an exception in this case
}
}
else // if you don't care
{
do nothing
}
}
if (everything went OK)
{
finally delete the record itself
}
------
if you specify DONTCARE you'll get current behaviour, but at least you are
acknowledged that it is now your responsibility to do same things manually.
This way we can get consistent behavior across databases while taking
advantage of available features.
Opinions?
>:-) Aren't you trying to write code for something that is already supported
by the
>RDBMS :-)
That's the problem. Somewhere it is supported, somewhere it is not and I'd
like consistent behavior....
fedor.
_______________________________________________________
Say Bye to Slow Internet!
http://www.home.com/xinbox/signup.html
------------------------------------------------------------
To subscribe: [EMAIL PROTECTED]
To unsubscribe: [EMAIL PROTECTED]
Search: <http://www.mail-archive.com/turbine%40list.working-dogs.com/>
Problems?: [EMAIL PROTECTED]
