Dear Experts,
My question is:
Is there any Jena implementation that can execute Aggregate function like
count, sum etc? Iterative counting of all elements could an option,
however, I want to know about direct implement of below method.
such as, the below method
------------------------------
------------------------------------------------------------------------
public void queryExecutor(VirtGraph dataset) {
String query =
"select distinct ?T1 ?T2 count(*) "+
"from <http://dbpedia.org> "+
"where "+
"{ "+
"?s1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?T1. "+
"?s2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?T2. "+
"?s1 <http://dbpedia.org/property/spouse> ?s2. "+
"?s2 <http://dbpedia.org/property/birthPlace> ?obj. "+
"FILTER(REGEX(?T1, \"http://dbpedia.org/ontology/\";)). "+
"FILTER(REGEX(?T2, \"http://dbpedia.org/ontology/\";)). "+
"}"+
"group by ?T1 ?T2 ";
System.out.println(query);
Query sparql1 = QueryFactory.create(query, Syntax.syntaxSPARQL_11);
try {
VirtuosoQueryExecution vqe1 =
VirtuosoQueryExecutionFactory.create(sparql1, dataset);
ResultSet results1 = vqe1.execSelect();
}
catch (Exception e) {
System.out.println("Error in query execution: " + e.toString());
e.printStackTrace();
}
}
-----------------------------------------------------------------------------------------------------------
-
Regards
Mizan
NII, Japan
---------- Forwarded message ----------
From: Md Mizanur Rahoman <[email protected]>
Date: Wed, May 7, 2014 at 7:35 PM
Subject: Group By Query in Jena Java
To: [email protected]
Dear Expert,
I want to execute a group by query in Jena. I am using Jena V2.6.4. But it
is giving exception
-----------------------------------------------------------------------------------------------------
Exception in thread "main" com.hp.hpl.jena.query.QueryParseException:
Encountered " "count" "count "" at line 1, column 26.
------------------------------------------------------------------------------------------------------
And here is my method,
------------------------------------------------------------------------------------------------------
public void queryExecutor(VirtGraph dataset) {
String query =
"select distinct ?T1 ?T2 count(*) "+
"from <http://dbpedia.org> "+
"where "+
"{ "+
"?s1 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?T1. "+
"?s2 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> ?T2. "+
"?s1 <http://dbpedia.org/property/spouse> ?s2. "+
"?s2 <http://dbpedia.org/property/birthPlace> ?obj. "+
"FILTER(REGEX(?T1, \"http://dbpedia.org/ontology/\";)). "+
"FILTER(REGEX(?T2, \"http://dbpedia.org/ontology/\";)). "+
"}"+
"group by ?T1 ?T2 ";
System.out.println(query);
Query sparql1 = QueryFactory.create(query, Syntax.syntaxSPARQL_11);
try {
VirtuosoQueryExecution vqe1 =
VirtuosoQueryExecutionFactory.create(sparql1, dataset);
ResultSet results1 = vqe1.execSelect();
}
catch (Exception e) {
System.out.println("Error in query execution: " + e.toString());
e.printStackTrace();
}
}
-----------------------------------------------------------------------------------------------------------
My question is:
* Is there any Jena version that can execute Aggregate function like count,
sum etc?
-
Regards
Mizanur
NII, Japan
