Re: Hierarchical queries and indexes
From: Paul <paul_at_test.com>
Date: Sat, 09 Oct 2004 13:30:14 +0100
Message-ID: <4167d9d4$0$44850$ed2619ec_at_ptn-nntp-reader02.plus.net>
Date: Sat, 09 Oct 2004 13:30:14 +0100
Message-ID: <4167d9d4$0$44850$ed2619ec_at_ptn-nntp-reader02.plus.net>
Troels Arvin wrote:
> Hello,> I realize that hypothetical thoughts on how things could/should be done in
> RDBMSes sometimes conflict with potential implementation difficulties,
> backwards compatiblity issues, etc. - But since this is a theory-group, I
> hope someone is interested in discussing why hierarchical encoding models
> have to exist.
Hierarchies have to be done in SQL as "encodings" (rather than directly) because they require second-order logic, and SQL is first-order logic.
Paul. Received on Sat Oct 09 2004 - 14:30:14 CEST