Re: Dawn doesn't like 1NF
From: Mikito Harakiri <mikharakiri_at_iahu.com>
Date: Wed, 20 Oct 2004 13:33:09 -0700
Message-ID: <oaAdd.62$A24.77_at_news.oracle.com>
Date: Wed, 20 Oct 2004 13:33:09 -0700
Message-ID: <oaAdd.62$A24.77_at_news.oracle.com>
"Paul" <paul_at_test.com> wrote in message
news:4173739e$0$59437$ed2619ec_at_ptn-nntp-reader03.plus.net...
> The problem arises when people think you should be able to access the
> "inner" relation *directly* from the external database engine. e.g.
> something like:
>
> SELECT * FROM RELATION (SELECT foo FROM bar WHERE id = 123)
This example hits it in the nail: instead of simplicity of nesting inner views (relational closure), one have to make 3(!) assumptions:
- SELECT foo FROM bar WHERE id = 123 is a scalar subquery.
- The type of bar.foo is nested table, not a scalar
- Typecast the scalar into a relation.
Every of this steps introduces a potential for an (parse- or runtime) exception. Received on Wed Oct 20 2004 - 22:33:09 CEST