- From: Steve Harris <steve.harris@garlik.com>
- Date: Thu, 12 Mar 2009 10:33:25 +0000
- To: SPARQL Working Group <public-rdf-dawg@w3.org>
On 12 Mar 2009, at 06:39, Lee Feigenbaum wrote: > The idea of using ASK queries in expressions appeals to me as well, > though it doesn't necessarily read as well as !EXISTS in SQL. The > verbosity is similar though, I guess. Similar, and it's one less bit of syntax. My personal preference is for fewer, more flexible verbs. But it's just a matter of taste. > I'm curious as to the interplay between: > > projected expressions > sub-selects > assignment > > Is there a combination of these that makes the 3rd irrelevant? Or > pairs of them that are far more useful when included together? > That's the sort of thing I'm working to wrap my head around. Yes, if you have projected expressions then you effectively get assignments: SELECT ?x WHERE { ?x :age ?age . FILTER(?age >= ?min_age) (SELECT 18 AS ?min_age) } Is equivalent to: SELECT ?x WHERE { ?x :age ?age . FILTER(?age >= ?min_age) LET(?min_age := 18) } - Steve -- Steve Harris Garlik Limited 2 Sheen Road Richmond TW9 1AE T +44(0)20 8973 2465 F +44(0)20 8973 2301 www.garlik.com Registered in England and Wales 535 7233 VAT # 849 0517 11 Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
Received on Thursday, 12 March 2009 10:34:01 UTC