Re: Modeling General Graphs in SQL
From: Mikito Harakiri <mikharakiri_nospaum_at_yahoo.com>
Date: 28 Dec 2005 10:20:34 -0800
Message-ID: <1135794034.512651.319730_at_o13g2000cwo.googlegroups.com>
Date: 28 Dec 2005 10:20:34 -0800
Message-ID: <1135794034.512651.319730_at_o13g2000cwo.googlegroups.com>
paul c wrote:
> >>>... which is
> >>>widely believed to be inexpresible by standard
> >>> SQL.
-------------------------------------------------------^^^^^^^^^^
> From "Universality of Data Retrieval Languages" by Alfred V. Aho and
> Jeffrey D. Ullman:
>
> "In this appendix. we prove that the transitive closure of a relation
> cannot be couched as an expression of
> relational algebra."
----------------------------------------------------^^^^^^^^^^^^^^^^^^^Received on Wed Dec 28 2005 - 19:20:34 CET