- From: Steve Harris <steve.harris@garlik.com>
- Date: Mon, 16 Nov 2009 20:35:00 +0000
- To: Andy Seaborne <andy.seaborne@talis.com>
- Cc: "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
On 16 Nov 2009, at 20:14, Andy Seaborne wrote: ... >> ?x = :alice, ?bestDay = 12 >> ?x = :bob, ?bestDay = 8 >> [no row for :carol because we can't return "unbound"/null from MAX(? >> sales)] >> > > Would this work? > > SELECT ?x ( TRY(MAX(?sales), -1) AS ?bestDay) > > or other choice of marker for no value. Yes, in this case, but it's a pretty poor substitute. I wonder if there's some wording where unbound expressions can be projected, it seems a little odd that SELECT ?sales produces rows, whereas SELECT COALESCE(?sales) doesn't. Probably if you chase this deep enough though you end up changing SPARQL 1.0 results :( I guess we should have bitten the bullet and gone with a tri-value logic to start with. - Steve PS I really don't like TRY() as a name, though I can see the logic in it. -- Steve Harris, CTO, Garlik Limited 2 Sheen Road, Richmond, TW9 1AE, UK +44(0)20 8973 2465 http://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 Monday, 16 November 2009 20:35:30 UTC