Re: Modeling General Graphs in SQL
From: paul c <toledobythesea_at_oohay.ac>
Date: Wed, 28 Dec 2005 21:54:24 GMT
Message-ID: <kQDsf.214234$Gd6.207889_at_pd7tw3no>
>
Date: Wed, 28 Dec 2005 21:54:24 GMT
Message-ID: <kQDsf.214234$Gd6.207889_at_pd7tw3no>
Mikito Harakiri wrote:
> 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.">
>
> ----------------------------------------------------^^^^^^^^^^^^^^^^^^^
Yes.
p Received on Wed Dec 28 2005 - 22:54:24 CET