I confess I never used triggers or RI with VFP tables. I would rather use my
own logic and code whatever is needed to achieve the same result.
Reasons: whenever I tried to figure out the built in code for RI that comes
with VFP I found myself at a loss to understand it. It is far too complicated.
Besides, whatever error messages it displays are in English and, in this
country, my users speak Spanish.
Another reason is that I prefer to have full control over my code, so I write
my own routines to deal with referential integrity.
However, only last week I created a new table and wanted to experiment with the
triggers. I simply wanted to set up Add, delete and modify triggers for one
field, a datetime field called DT.
What I did is put the datetime() function in each of the trigger fields. My
intention was that whenever I add, modify or delete a record in this table, the
DT field would be updated with the current datetime.
I get an error message: cannot modify record because the table is readonly.
Is this by design and if so, why?
Is there a workaround?
(I know, I can code that in my form, but was wondering whether triggers would
do)
Please, clarify.
Rafael Copquin
----- Original Message -----
From: Garrett Fitzgerald
To: [EMAIL PROTECTED]
Sent: Friday, May 30, 2008 2:16 PM
Subject: Re: Relationships and referential integrity
That scares me on general principles. I think it would be much better to
write application logic to check if there are lines left: after all, you
could be deleting records and adding new ones, right?
But you could probably do that with a Delete Trigger on the child table if
you really had to.
On Fri, May 30, 2008 at 12:54 PM, John J. Mihaljevic <
[EMAIL PROTECTED]> wrote:
> Hi all,
>
> In a one-to-many relationship, I can easily see how to automatically delete
> any child records when the corresponding parent record is deleted. But how
> is this done in reverse? When the final child record of a relationship is
> deleted, can the parent record automatically be deleted in some way? The
> example I'm using is an order. When the final detail line of the order is
> completed (and the record is deleted from the OrderDetail table), I'd like
> the order header to automatically be deleted from the OrderHeader table.
>
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