Re: Nested SELECT with LIMIT

[baran_H]

Andy, thank you very much for your quick and detailed reply, i think i understand now logic of 'bottom-to-top' SPARQL evaluation for sub-selects, i could also other tests get working with this logic. But i see a test-case for 'SubSelect with LIMIT' in http://www.w3.org/2009/sparql/wiki/Design:SubSelect I guess the output there is the result of 'top to bottom' evaluation and therefore with Joseki 3.4.3 i cannot get that result?? Or do i overlook some other detail to get this test-case work? --------------------------------------------- @prefix : <http://people.example/> . :alice :name "Alice", "Alice Foo", "A. Foo" . :alice :knows :bob, :carol . :bob :name "Bob", "Bob Bar", "B. Bar" . :carol :name "Carol", "Carol Baz", "C. Baz" . --------------------------------------------- PREFIX : <http://people.example/> SELECT ?y ?name WHERE { :alice :knows ?y . {SELECT ?y ?name WHERE {  ?y :name ?name }ORDER BY ?name LIMIT 1 }} -------------------------------------------- result: ?y     ?name         :bob   "B. Bar"         :carol "C. Baz" -------------------------------------------- thanks, baran.   On Mon, 07 Mar 2011 16:54:25 +0100, Andy Seaborne <andy.seabo...@epimorphics.com> wrote: > SPARQL evaluation is bottom-to-top (functional). Evaluate the arguments > then combine them, just like a programming language: > > f(3+4, 5+6) => f(7, 11) => .... > > Evaluate the two parts: > > 1/ The inner select evaluates to one row: > > ?x = <http://dbpedia.org/resource/Dynamic_programming> > ?y ="Dynamische Programmierung"@de > > 2/ The ?x dcterms:subject dbpc:Optimal_control evaluates to two rows: > > ?x = http://dbpedia.org/resource/Optimal_control > > and > > ?x = http://dbpedia.org/resource/Dynamic_programming > > Combine these with a join: > > When you join those there is one answer: > > ?x = <http://dbpedia.org/resource/Dynamic_programming> > > There will be no results with > > ?x = http://dbpedia.org/resource/Optimal_control > > It is common to read from top to bottom but it's not always right (and > in the past, ARQ has got this wrong with sub-selects as well). > > Andy > > -------------------------------------------------------------------------------------- > > On 07/03/11 15:20, baran_H wrote: >> Hello, i test with Joseki 3.4.3 >> ---------------------------------------------------------------- >> PREFIX dbpc: <http://dbpedia.org/resource/Category:> >> PREFIX dbpo: <http://dbpedia.org/ontology/> >> PREFIX dcterms: <http://purl.org/dc/terms/> >> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> >> SELECT ?x ?y >> FROM <http://dbpedia.org/resource/Dynamic_programming> >> FROM <http://dbpedia.org/resource/Optimal_control> >> WHERE {?x dcterms:subject dbpc:Optimal_control . >> {SELECT ?x ?y WHERE >> {?x rdfs:label ?y . FILTER (lang(?y) = 'en' || lang(?y) = 'de') >> }ORDER BY (lang(?y)) LIMIT 1 >> }} >> ---------------------------------------------------------------- >> >> WITHOUT LIMIT 1 i get: >> <../Optimal_control> "Optimal control"@en >> <../Dynamic_programming> "Dynamische Programmierung"@de >> <../Dynamic_programming> "Dynamic programming"@en >> >> WITH LIMIT 1 i get: >> <../Dynamic_programming> "Dynamische Programmierung"@de >> >> I think now: This is coreect if LIMIT 1 is at the end of the query, but >> LIMIT 1 for nested SELECT should effect, like ORDER BY (lang(?y)) does, >> only results with identical ?x, because >> ?x dcterms:subject dbpc:Optimal_control >> is outer nested SELECT, in the results this is: <../Dynamic_programming> >> >> and therefore with LIMIT 1 i expect (??) : >> >> <../Optimal_control> "Optimal control"@en >> <../Dynamic_programming> "Dynamische Programmierung"@de >> >> thanks, baran. >> >> -- >> Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/