--- In firebird-support@yahoogroups.com, "Martijn Tonies"
<m.tonies@u...> wrote:

>
> > > > I have some tables that contain records that the user should

not

> > be
> > > > able to modify or delete. Other records in the same table
> > should be
> > > > freely modified, deleted, whatever. I'm trying to come up

with

> > > > an 'on update or delete' trigger that will prevent the

change if

> > a
> > > > field value exists.
> > > >
> > > > if (NEW.SomeField = 0) then
> > > > DoNotChangeMe;
> > > >
> > > > Is something like this possible from within a trigger or is
> > there a
> > > > better way to protect these records at the server level?
> > >
> > > You can do this via a trigger that raises an exception...
> > >
> > > Here's an example:
> > > CREATE EXCEPTION DELETE_NOT_ALLOWED 'System data - not allowed

to

> > delete
> > > this.';
> > >
> > >
> > > SET TERM ^^ ;
> > > CREATE TRIGGER CATEGORIE_SYSTEEM FOR CATEGORIE ACTIVE BEFORE
> > DELETE POSITION
> > > 0 AS
> > > BEGIN
> > > if (old.SYSTEEM = 'T')
> > > then exception DELETE_NOT_ALLOWED;
> > > END
> > > ^^
> > > SET TERM ; ^^
> > >
> > > Of course, you DO need to handle the exception :-)
> >
> > I can see where this would work but I would prefer that the

server

> > just disallow the deletion. I don't want my client application

to

> > have to handle the exception; I just want the record to not be
> > deleted. Is there another way?
>
> Define "just disallow" --
>
> * raise an exception?
> * ignore the DELETE?
>
> How would this work, what would be your feedback?

I don't need an exception or any feedback. I just want the server
to not delete the record.

Steve