At 09:18 AM 08-02-01 +0100, you wrote:

>Helen,
>whereas I fully agree that mixing generators and other ways to assign
>primary keys are bound to get you into trouble, I see Michaels code as only
>an attempt to cover for stupidity in case someone should assign a PK
>without using the generator. Note that he only increases the generator,
>never decreases. This could lead to holes in the PK sequence, but not PK
>violations due to the generator.
>
>Set

Svein,
read the original code again!! This trigger is going to fire on **every**
insert and blat whatever value comes through.
<g>

Helen

>At 09:48 08.02.2001 +1100, you wrote:
> >At 04:11 PM 07-02-01 -0500, you wrote:
> >>Hello Paul
> >>
> >>GeneratorLinks is to allow IBO to go ahead and get the
> >>ID of the record before the actual insert. This allows
> >>it to pass it along to Detail tables that could be connected
> >>and other things. You don't have to use it for positioning,
> >>I think you are talking about keylinks.
> >>
> >>I use the following trigger on my tables:
> >>
> >> create trigger TRGBEFINS_Customer for Customer
> >> active before insert position 0
> >> as
> >> DECLARE VARIABLE Temp_ID integer;
> >> begin
> >> if ((new.Cus_ID is NULL) or (new.cus_ID = 0)) then
> >> begin
> >> new.Cus_ID = gen_id (Gen_Customer_ID, 1);
> >
> >END THE TRIGGER HERE !!!
> >
> >The following code is !!!! dangerous !!!!. Generators operate right
> >outside the transaction context. In a multi-user environment, you are
> >certain to get PK violations. Don't do it!!!
> >
> >> end else begin
> >> Temp_ID = gen_id(Gen_Customer_ID,0);
> >> if (new.CUS_ID > Temp_ID) then
> >> begin
> >> Temp_ID = gen_id(Gen_Customer_ID, new.Cus_ID-Temp_ID);
> >> end
> >> end
> >> end
> >>
> >>It will update your generator if necessary and also, make
> >>sure that the generator doesn't get behind if you inserted
> >>records that had IDs not derived from the generator.
> >
> >If you are using a generator to populate a primary key, you should NEVER
> >try to insert rows where the PK comes from another source that **that**
> >generator.
> >
> >To add a further note on GeneratorLinks, you should always use it when
> >inserting into a bi-directional dataset, rather than waiting until after
> >the insert has committed, to ensure that the KeyLinks will work
> >properly. Reserve the use of the trigger for external clients or scripts.
> >
> >Helen
> >
> >
> >
> >
> >All for Open and Open for All
> >InterBase Developer Initiative · http://www.interbase2000.org
> >_______________________________________________________
> >
> >
> >
> >
> >
>
>

All for Open and Open for All
InterBase Developer Initiative · http://www.interbase2000.org
_______________________________________________________