Re: Trigger to delete record from one table with check on another table.

From: Kenneth Osenbroch <kenneth.osenbroch_at_telenor.com>
Date: 8 Jun 2004 00:29:48 -0700
Message-ID: <ce7df6a2.0406072329.a7d522c_at_posting.google.com>


ed.prochak_at_magicinterface.com (Ed prochak) wrote in message news:<4b5394b2.0406031025.3f01745e_at_posting.google.com>...
> kenneth.osenbroch_at_telenor.com (Kenneth Osenbroch) wrote in message news:<ce7df6a2.0406030112.2b7f3e5b_at_posting.google.com>...
> > ed.prochak_at_magicinterface.com (Ed prochak) wrote in message news:<4b5394b2.0405260843.2029300c@posting.google.com>...
> > > kenneth.osenbroch_at_telenor.com (Kenneth Osenbroch) wrote in message news:<ce7df6a2.0405260105.55c4489_at_posting.google.com>...
> > > > Hi. I want to create a trigger that only allows delete from table A if
> > > > corresponding record in table B does not exist. Any idea on how this
> > > > can be done? Thanks, Kenneth.
> > >
> > > Sounds more like you want a reference constraint.
> > > Do you have Primary keys and Foreign Keys set up on the corredsponding
> > > tables? Looks like from the description table A is the parent table
> > > (wiht a primary key) and table B is the child table (with a foreign
> > > key that references the primary key of table A)
> > >
> > > HTH,
> > > ed
> >
> > Hi, and thanks for your reply.
> >
> > The thing is that it is not possible to use constraints based on PK's
> > and FK's in this database (the relations are placed on the applicaton
> > layer - hence it doesn't exist any PK's or FK's).
> >
> > So: I figure trigger is the only solution to ensure the above
> > scenario. Any ideas on how the trigger would look?
> >
> > Thanks,
> > Kenneth
>
> I cannot think of any way for a trigger to STOP a delete, other than
> maybe throwing an exception?
>
> What do you mean the relations are in the application layer?
> (CAUTION: That's the path to hell!)
>
> Do you have two tables in the database or not?
>
> It looks like you are using a screwdriver as a hammer. It doesn't work
> well and in the end both the nail and the screwdriver are in bad
> shape.
>
> Sorry I cannot be more help, but I have a genetic disorder that
> debilitates my programming skills when faced with an absurd
> assignment. 8^)
>
> Good luck! you are going to need it.
> Ed

:o)

I know! Consider the case closed.

Cheers,
Kenneth Received on Tue Jun 08 2004 - 09:29:48 CEST

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