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(unknown charset) Re: why query languages and RDF data have syntaxes?

From: (unknown charset) Dan Brickley <danbri@w3.org>
Date: Thu, 28 Nov 2002 23:24:17 -0500
To: (unknown charset) JeffZhang <jeffzhang726@yahoo.com.cn>
Cc: (unknown charset) "www-rdf-interest@w3.org" <www-rdf-interest@w3.org>
Message-ID: <20021128232417.B12158@tux.w3.org>

* JeffZhang <jeffzhang726@yahoo.com.cn> [2002-11-29 12:21-0800]
> 
> Dear allúČ
>     I can not understand why syntaxes of several current rdf query languages are so much different
> with the syntax of RDF data. In my opinion, a query is match a pattern(a subgraph with 
> undetermined values) against the universal(the big graph in knowledge base). Why not use 
> just a small rdf data set with blank nodes to represent the subgraph? 
> I think these query languages have more close relation with sql than with rdf model.

The main reason people use non-RDF syntax, is so they can be very clear 
as to which bits are being marked as 'unknowns'. For the common-enough case
where you're not marking an edge as unknown, you're right, a 'query by example' approach is useful and can be implemented on top of the existing RDF/XML 
syntax. This maps to Squish, RDFdb-ql, Algae, RDQL etc, especially if you 
decorate the unknown nodes with an additional property/value pair encoding 
a variable name...

Dan
Received on Thursday, 28 November 2002 23:24:18 GMT

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