Re: select coauthors

Thu, 20 Oct 2011 05:49:12 -0700 

So your query is:

[[

SELECT ?name ?title
 {
    ?s dc:title ?title.
    ?o foaf:name ?name.
    ?o foaf:name "Donald D. Chamberlin"
 }
LIMIT 5

]]
That doesn't do what you think it does, because it does relate ?o to ?s. ?o can be anything with a foaf:name property of "Donald D. Chamberlin" and ?name will return all the values for the foaf:name property for that resource - there is only one - "Donald D. Chamberlin".
What you need to do is get a query that will return the other authors of the publication, e.g. 

SELECT ?coauthorName ?title
WHERE {
?author foaf:name "Donald D. Chamberlin" . # put first as its most restrictive ?publication <editor> ?author . # now select all the publications with that author as editor 
# you didn't provide a namespace for the editor property
?title dc:title ?title # get the title of the publication
?publication <editor> ?coauthor . # now find all the authors of that publication 
FILTER (?coauthor != ?author) # eliminate the original author specified
?coauthor foaf:name ?coauthorName # get the name of the coauthor

# done
}

On 20/10/2011 11:41, Ján Mojžiš wrote:

Hi there,
I have a following-type records:

<rdf:Description
rdf:about="http://www.w3.org/TR/xquery";><dc:identifier>www/org/w3/TR/xquery</dc:identifier><dc:date>2002-01-03</dc:date><rdf:type
rdf:resource="http://sw.deri.org/~aharth/2004/07/dblp/dblp.owl#Www"/>
<editor><foaf:Person rdf:nodeID="DonaldDChamberlin"><foaf:name>Donald D.
Chamberlin</foaf:name></foaf:Person></editor>
<editor><foaf:Person rdf:nodeID="DanielaFlorescu"><foaf:name>Daniela
Florescu</foaf:name></foaf:Person></editor>
<editor><foaf:Person rdf:nodeID="JonathanRobie"><foaf:name>Jonathan
Robie</foaf:name></foaf:Person></editor>
<editor><foaf:Person
rdf:nodeID="J&#xE9;r&#xF4;meSim&#xE9;on"><foaf:name>J&#xE9;r&#xF4;me
Sim&#xE9;on</foaf:name></foaf:Person></editor>
<editor><foaf:Person rdf:nodeID="MugurStefanescu"><foaf:name>Mugur
Stefanescu</foaf:name></foaf:Person></editor>
<dc:title rdf:parseType="Literal">XQuery: A Query Language for
XML</dc:title>
<year>2001</year>

They are books or publications, where each one can have multiple authors
(co-authors).

First I search books based on foaf:person - one author. To get his
publications. My working query is:

PREFIX foaf:<http://xmlns.com/foaf/0.1/>
PREFIX rdf:<http://www.w3.org/1999/02/22-rdf-syntax-ns#>     #type
PREFIX dc:<http://purl.org/dc/elements/1.1/>      # identifier, date,
creator, title
SELECT ?name ?title
  {
     ?s dc:title ?title.
     ?o foaf:name ?name.
     ?o foaf:name "Donald D. Chamberlin"
  }
LIMIT 5

It returns
------------------------------------------------------------------------------------------------------
| name                   |
title
======================================================================================================
| "Donald D. Chamberlin" | "PRPL: A Database Workload Specification
Language, v1.3."^^rdf:XMLLiteral
| "Donald D. Chamberlin" | "Efficient View Maintenance at Data
Warehouses."^^rdf:XMLLiteral
| "Donald D. Chamberlin" | "Self-organizing
Map"^^rdf:XMLLiteral
| "Donald D. Chamberlin" | "Beowulf Project at
CESDIS"^^rdf:XMLLiteral
| "Donald D. Chamberlin" | "The MPEG Home
Page"^^rdf:XMLLiteral
------------------------------------------------------------------------------------------------------

But also I want co-authors of each found match! NOW how to get co-authors? I
have spent many hours trying to get co-authors in single query, with no
success.
Please be so kind to help.

Many thanks
Jan

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