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RE: variables prefix - ?variable vs. $variable

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Tue, 31 Aug 2004 17:57:27 +0100
Message-ID: <E864E95CB35C1C46B72FEA0626A2E80803E3C16F@0-mail-br1.hpl.hp.com>
To: RDF Data Access Working Group <public-rdf-dawg@w3.org>




-------- Original Message --------
> From: Dirk-Willem van Gulik <>
> Date: 31 August 2004 14:20
> 
> On Tue, 31 Aug 2004, Kendall Clark wrote:
> 
> > Sorry, I don't mean to be nasty, the asemantics guys are great!, but
> > these are all much worse than "?foo".
> 
> Pick another one then :) - pretty much all other chars are safe except
> for 
> the surrounders, _ and % if you ignore languages and just consider DB
> interfaces.
> 
> How about
> 
> 	select =id, =title
> 	where (=id ...

variabnles appear elsewhere so this means

  =x == =y
for
  ?x == ?y

Parsers have no problems with this stuff - people do!

> 
> to signal the 'link' ? OR how about just dropping it completely
> 
> 	select id title
> 	from <dbms://localhost/rfid>
> 	where (id foo:id <urn:froefroe...
> 		..
> 	using foo ...
> 
> by simply insisting that any and all literals have a "" or '' , URI's
> always have a <> around them and anything else must use a : separator
> for the namepsace ?

May work but others have objected to grammars that have lookahead >1.  This
has - need to look over the NCNAME to see if there is a :.

x :p is var-x, followed by :p with the default namespace 
x:p is a qname.

Confusing or what?

And quds make it worse as a triple pattern + a space can become a valid quad
pattern.

> 
> Also think of the upside; do this right and you can instantly allow ANY
> language/installation which has an ODBC, JDBC, ADO, whatever SQL
> interface 
> do semantic web queries with virtually no rework on the client side. AND
> you get at least some instant buy in from the people currently in
> control 
> of data storage and the SQL bastion.

We aren't querying existing SQL databases.

> 
> Dw
Received on Tuesday, 31 August 2004 16:58:10 GMT

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