Rene Nyffenegger <rene.nyffenegger_at_gmx.ch> wrote in message news:<slrncl0j67.28k.rene.nyffenegger_at_zhnt60m34.netarchitects.com>...
> In article <f858471c.0409210721.3a828218_at_posting.google.com>, Ben Graham wrote:
> > avanrossem_at_hotmail.com (Andre) wrote in message news:<4d32d1be.0409210219.26642641_at_posting.google.com>...
> >> Hello all,
> >>
> >> I have created an insert trigger:
> >> If I do a count on the table and this count results in a 1 or higher I
> >> would not insert the record. (of_id is not the primary key)
> >>
> > CREATE OR REPLACE TRIGGER iu_cli BEFORE insert or update on client
> > FOR EACH ROW
> > DECLARE
> > CC number;
> > BEGIN
> > IF INSERTING
> > THEN
> > select count(*) into CC from client WHERE of_id = :new.of_id;
> > If CC > 0 then
> > --do not insert
> > raise_application_error(-20000,'Invalid of_id. Your message here');
> > end if;
> > END IF;
> > END;
> > /
>
>
> That's most probably not what the OP wants
>
> Consider
>
> create table client (
> of_id number,
> foooo number
> );
>
>
> CREATE OR REPLACE TRIGGER iu_cli BEFORE insert or update on client
> FOR EACH ROW
> DECLARE
> CC number;
> BEGIN
> IF INSERTING
> THEN
> select count(*) into CC from client WHERE of_id = :new.of_id;
> If CC > 0 then
> --do not insert
> raise_application_error(-20000,'Invalid of_id. Your message here');
> end if;
> END IF;
> END;
> /
>
> --- Run the following PL/SQL block
> --- simultanously in two SQL*Plus
> --- sessions
>
> begin
> for i in 1 .. 50000 loop
> begin
> insert into client values
> (mod(i,20), i);
> exception when others then null;
> end;
> end loop;
> end;
> /
>
> commit;
>
> -------------- Then....
>
> select count(*), of_id from client group by of_id;
>
>
> COUNT(*) OF_ID
> ---------- ----------
> 2 0
> 2 1
> 2 2
> 2 3
> 2 4
> 2 5
> 2 6
> 2 7
> 2 8
> 2 9
> 2 10
> 2 11
> 2 12
> 2 13
> 2 14
> 2 15
> 2 16
> 2 17
> 2 18
> 2 19
>
>
> > ...or create an unique constraint on client.of_id:
> >
> > alter table client
> > add constraint client_of_id_uni
> > unique (of_id);
>
> Definitely the better approach.
>
> Rene
Hello all,
Well, the unique index is not an option. So I will not do that. I had
implementen the raise-application-error but I was wondering if there
was a more elegenat sollution.
Thanks all for helping me!
Anneke.
Received on Wed Sep 22 2004 - 00:11:23 CDT
