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AGSparqlSetWithVariables.java

package com.franz.agbase.examples;



import com.franz.agbase.AllegroGraphException;

import com.franz.agbase.AllegroGraph;

import com.franz.agbase.AllegroGraphConnection;

import com.franz.agbase.BlankNode;

import com.franz.agbase.LiteralNode;

import com.franz.agbase.SPARQLQuery;

import com.franz.agbase.ValueSetIterator;





public class AGSparqlSetWithVariables {



    /**

     * Demonstrates how to bind variables in a SPARQL query.

     * 

     * @param args unused

     * @throws AllegroGraphException 

     */

    public static void main(String[] args) throws AllegroGraphException {

        

        // Connect to server, which must already be running.

        AllegroGraphConnection ags = new AllegroGraphConnection();

        try {

            ags.enable();

        } catch (Exception e) {

            throw new AllegroGraphException("Server connection problem", e);

        }

        

        // Create fresh triple-store for this example.

        AllegroGraph ts = ags.renew("sparql", AGPaths.TRIPLE_STORES);

                

        // Register any namespaces

        ts.registerNamespace("ex", "http://example.org/");

        

        // Define blank nodes

        BlankNode a = (BlankNode)ts.createBNode("_:a");

        BlankNode b = (BlankNode)ts.createBNode("_:b");

        

        // Add some data to the store

        LiteralNode aliceName = ts.createLiteral("Alice");

        ts.addStatement(a,"!ex:employeeName", aliceName);

        ts.addStatement(a,"!ex:employeeId",ts.createLiteral(12345));

        ts.addStatement(b,"!ex:employeeName",ts.createLiteral("Bob"));

        ts.addStatement(b,"!ex:employeeId",ts.createLiteral(67890));



        String query =

        "PREFIX ex: <http://example.org/> " +

        "SELECT ?s ?o " +

        "WHERE  { ?s ex:employeeName ?o }";

        

        // Query the store and show the results

        SPARQLQuery sq = new SPARQLQuery();

        sq.setTripleStore(ts);

        sq.setQuery(query);

        ValueSetIterator it = sq.select();

        AGUtils.showResults(it);



        // Bind the variable ?o and reissue the query

        Object[] varvals = new Object[2];

        varvals[0] = "o";

        varvals[1] = aliceName;

        sq.setWithVariables(ts, varvals);

        it = sq.select();

        AGUtils.showResults(it);

        

        // Close the triple store and disconnect from the server.

        ts.closeTripleStore();

        ags.disable();

    }



}
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