Subject Re: How can I skip an Insert ?
Author yazbeckmona
--- In, "Adam" <s3057043@y...> wrote:
> --- In, "yazbeckmona"
> <yazbeckmona@y...> wrote:
> > Hello,
> >
> > I would like to add something to my trigger "BeforeInsert" that
> would
> > ignore every line that is already in the database. How could I do
> > that, I have absolutely no idea, I never worked with trigger
> before! I
> > need to NOT insert lines that is already in the database (of
> course,
> > because now I have some primary key duplicate error). (And I
> > want to change my SQL query, because I tried already everything
> it
> > is terribly long.)
> >
> > Here's my trigger with a key generator:
> > AS
> > if (NEW.idemployeur IS null) then
> > NEW.idEmployeur = GEN_ID(G_EmployeuridEmployeurGen7, 1);
> > END
> >
> > Thank you so much for any help!
> Triggers do not appear to be what you want.
> You seem a little confused about the role of the queries etc.
> Firebird will raise an exception if your primary key is not unique.
> In other words, you must be supplying a idEmployeur that is already
> in the table (a duplicate), and that is against the whole concept
> a primary key. Your application should catch the exception and
> accordingly. It would be very confusing logic to have the database
> quietly eat any duplicate data, you would not then know where your
> record went. Instead, you now have a mechanism where the database
> informs you that the query operation failed, and why it failed. Use
> it to your advantage.
> In fact, the way you would do input validation in the before insert
> trigger would be to raise a custom exception to prevent the insert
> from succeeding.
> Adam


The thing I am trying to do is that I have 2 tables (tab1 and tab2).
I want to store the data form tab1 in tab2 IF tab2 doesn't already
have it. It is so simple, I do this usually but now, the table are
too large and when I write my query using something like
INSERT id, c1, c2, c3 IN tab2 FROM tab1 WHERE NOT EXISTS (SELECT id
FROM tab2 WHERE = it is really terribly long.

So that's why I wanted to skip the insert instead. So How can I write
a try and catch exception in the trigger? Hopping it will be a little
faster than the query...