Hi all,

Yes you can have triggers on views. It's one of the big Ib/Fb
advantages. You can make views updatable even when SQL standard says
they aren't.

Try this on the employee.gdb's phone_list view:

> set term ^;
> create trigger phone_list_bu for phone_list before update
> as
> begin
> /* employee base table */
> update employee set phone_ext = new.phone_ext
> where emp_no = new.emp_no ;
> /* department base table */
> update department set location = new.location , phone_no = new.phone_no
> where dept_no = (select dept_no from employee where emp_no = new.emp_no);
> end
> ^
> set term ;^

However, in the case of your application, you should check validity as
close to the data as possible, i.e. on base tables. Preferrably in
declarative constraints, or otherwise in triggers.

Good luck,
Marco

Svein Erling Tysvaer wrote:

> No, you cannot have triggers on views, I thought you were going to use it
> so that it was impossible to overbook a hotel or something and then I
> thought it would be better to prevent that from happening by using a
> trigger (or check constraint) on the actual column that shouted NEJ when
> you tried to book a room that wasn't available.
>
> As for your view, I'm only curious as to why you use the old SQL-89
> notation. In general SQL-92 is recommended, i.e.
>
> CREATE VIEW VY_SANGPLATSER AS
> select V.PLATSID, P.PERSNR, P.FNAMN, P.ENAMN, V.SANGNR, V.RUMNR,
> A.AVDID, A.NAMN, P.KON, I.INSKRIVID, INTAG.INTAGID
> from TBLINSKRIVNING I
> join TBLINTAGNING INTAG on I.INSKRIVID = INTAG.INSKRIVID
> join TBLVARDPLATS V on V.PLATSID = INTAG.PLATSID
> join TBLAVDELNING A on A.AVDID = INTAG.AVDID
> join TBLPATIENT P on P.PERSNR = I.PERSNR
> ;
>
> (Easier to read and e.g. makes JoinLinks in IBO redundant)
> Set
>
> At 13:30 21.11.2002 +0000, you wrote:
> >Could this be acomplished witha a insert/uppdate trigger on this
> >following view where count is to be controlled on P.PERSNR is not
> >larger then 20:
> >
> >CREATE VIEW VY_SANGPLATSER AS
> >select V.PLATSID, P.PERSNR, P.FNAMN, P.ENAMN, V.SANGNR, V.RUMNR,
> >A.AVDID, A.NAMN, P.KON, I.INSKRIVID, INTAG.INTAGID
> >from TBLVARDPLATS V, TBLAVDELNING A, TBLPATIENT P, TBLINSKRIVNING I,
> >TBLINTAGNING INTAG
> >WHERE P.PERSNR = I.PERSNR
> >AND
> >V.PLATSID = INTAG.PLATSID
> >AND
> >A.AVDID = INTAG.AVDID
> >AND
> >I.INSKRIVID = INTAG.INSKRIVID
> >;
>
>
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