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From: bg0l+@andrew.cmu.edu (Bruce E. Golightly)
Newsgroups: comp.databases
Subject: Re: Oracle: Previous Record
Message-ID: <AYknCfy00WB28IU6sk@andrew.cmu.edu>
Date: 18 Jul 89 13:42:03 GMT
Organization: Carnegie Mellon, Pittsburgh, PA
Lines: 22

There are indeed times when you can't think in terms of the relational
model. Sometimes the users insist that they want what they want, and you
can't do it without breaking the model. We had to write an application
to do this kind of thing a while back.

We don't use Oracle here, we use Ingres. The problem is basically the same
using either, though. The suggestion that you use the ROWID (TID in Ingres)
has some merit. Relational Technology (Ingres) has repeated pointed out
that use of the tuple ID in user specified operations is not a supported
feature and that relying on characteristics of the TID may result in a
broken application some time. I suspect that Oracle would echo this.
Another method might be used, however. In Ingres I have occassionally set
up a tablefield that the user can't see on the screen and used it to store
the set of possible matches. The idea of PreviousRecord may then be
implemented by scrolling up in this table field and doing a simple SELECT
based on the result to fill in the visible portions of the screen. The
problem with this appraoch is that it requires lots more code.

I don't know if you can do something like that in Oracle, so take it
with a grain of salt.

Bruce