use:

if (exists(select ..)) then
throw ..

'exists' is true if 'select' found one or more records.

> -----Original Message-----
> From: PUB: rodbracher [mailto:rod@...]
> Sent: Miércoles, 26 de Junio de 2002 12:59
> To: ib-support@yahoogroups.com
> Subject: [ib-support] Re: Avoiding a delete
>
>
> I can't use a Referential Constraint as this is the 'wrong way round'.
> I am not sure how to get the trigger working properly
> It should look something like :
>
> set term ^ ;
> create trigger dealer_bd for dealer before delete as
> begin
> if select count(*) from Table_Sales , Table_Dealer where
> Table_sales.dealer = Table_Dealer.dealer > 0
> then exception my_exception
> end^
> set term ; ^
>
> IBcosole does not like the "Select" - can I do such a thing ?
> Will the dealer parameter be of the dealer the trigger was set off
> with ?
> --- In ib-support@y..., "Martijn Tonies" <m.tonies@u...> wrote:
> > Hi,
> >
> > Try either a BEFORE DELETE trigger that raises an exception
> > if there are records in Table_Sales or a Referential Constraint
> > that does this job for you. Check the Language Reference for
> > this.
> >
> > Martijn Tonies
> > InterBase Workbench - the developer tool for InterBase and Firebird
> > http://www.interbaseworkbench.com
> >
> > Upscene Productions
> > http://www.upscene.com
> >
> > "This is an object-oriented system.
> > If we change anything, the users object."
> >
> >
> > > Hi
> > >
> > > What is the best way to avoid deleting a record ( a dealer ) from
> > > Table_Dealer
> > > if its key_column is Dealer and this is a non-key column in
> > > Table_Sales.
> > >
> > > Ie no delete if the dealer has sales.
> > >
> > > Thanks
> > >
> > > Rod
>
>
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