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

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 Received on Thu Jun 03 2004 - 20:25:32 CEST