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Re: What databases have taught me

From: vc <boston103_at_hotmail.com>
Date: 23 Jun 2006 11:46:09 -0700
Message-ID: <1151088369.449869.319520@g10g2000cwb.googlegroups.com>

Bruno Desthuilliers wrote:
[...]
>. And all the litterature that keep on
> saying RA can't do this.

You are quite right that the RA (or the predicate logic of which the RA is a dialect) cannot express transitive closure. It has to be extended with some kind of the TC operator.

There is a standard (SQL'99) TC closure operator called 'recursive query'. Both DB2 and SQL Server 2005 have it. Oracle has had the proprietary 'connect by' since probably version 7. As far as I remember, Postgress used to have a patch that implemented the Oracle 'connect by'.

> bruno desthuilliers
> python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
> p in 'onurb_at_xiludom.gro'.split('@')])"
Received on Fri Jun 23 2006 - 13:46:09 CDT

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