In SPARQL, the only way a variable can get a value is from a basic graph pattern match – everything builds up from there – and only RDF terms in the graph can be bound so only RDF terms that occur in the graph can be returned and then used in the CONSTRUCT.
In ARQ, in the extended syntax, there is assignment:
{
…
?s ont:firstName ?firstName .
?s ont:lastName ?lastName .
LET ( ?name = fn:concat(?firstName, “ “, ?lastName) )
}
Where fn:concat [1][2] is the XQuery/XPath Function to concatenate strings.
There are other ways to achieve assignment; subqueries with SELECT expressions;
property functions, that give an enhanced view of the data within strict SPARQL
syntax.
A property function is custom code, made to fit into the SPARQl syntax, that
called at query execution time
PREFIX apf: <http://jena.hpl.hp.com/ARQ/property#>
prefix ont: <http://www.owl-ontologies.com/Ontology1200929459.owl>
SELECT *
{
?s ont:firstName ?firstName .
?s ont:lastName ?lastName .
?name apf:concat (?firstName “ “ ? lastName)
}
Will bind ?name to the result of concatenting str(?firstName) the space and
str(?lastName)
Andy
[1] http://www.w3.org/TR/xpath-functions/
[2] Only in SVN : in checking this reply, I found it was wrongly named and
fixed that.
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ricardo Almeida
Sent: 09 September 2008 15:15
To: [email protected]
Subject: SPARQL query - Construct
I,
I’m using sparql with Jena, to make some queries. I have two ontologies (src1
and tgt), and two rdf files were I have my instances, according to this
ontologies.
[cid:[email protected]]src1:
[cid:[email protected]] person: Set of
[cid:[email protected]] personId
[cid:[email protected]][cid:[EMAIL PROTECTED]
name
addressId
addressSrc: Set of
[cid:[email protected]]
adressIdSrc
[cid:[email protected]]street
[cid:[email protected]]
pobox
tgt:
employee: Set of
employee:
employeeId
firstName
lastName
addressId
addressTgt: Set of
adressIdTgt
address
I would like to use construct to obtain data from one ontology, according to
the other. Is it possible to make a concatenation (or a split), with construct?
I made the query described above and I obtain all the first names, but what I
really wanted was to obtain the concatenation of firstName and lastName, of tgt
as the name of src1.
private String QConstructSrcFromTgt =
"CONSTRUCT { ?s rdf:type
<http://www.owl-ontologies.com/Ontology1200929461.owl#Person> .." +
" ?s
<http://www.owl-ontologies.com/Ontology1200929461.owl#name> ?firstName" +
"} FROM <http://www.owl-ontologies.com/Ontology1200929459.owl> WHERE
{?s rdf:type ?o ." +
" ?s
<http://www.owl-ontologies.com/Ontology1200929459.owl#firstName> ?firstName} ";
//" ?s
<http://www.owl-ontologies.com/Ontology1200929459.owl#lasttName> ?lastName. "+
//" FILTER regex(?lastName, \"Castro\") } ";
Thanks,
Ricardo Gabriel Soares Fernandes de Almeida.
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