The Sesame database uses Java APIs to query and modify data. 1. query data to obtain the query data (through SPARQL) publicstaticvoidtestQuery () {try {RepositoryConnectionconrepo. getConnection (); try {StringqueryStringPREFIXrk: rk. comtest + SELECT? S
The Sesame database uses Java APIs to query and modify data. 1. query data (through SPARQL) public static void testQuery () {try {RepositoryConnection con = repo. getConnection (); try {String queryString = PREFIX rk: http://rk.com/test/ + SELECT? S
The Sesame database uses Java APIs to query and modify data.
1. query data to obtain the queried data (through SPARQL)
public static void testQuery() {try { RepositoryConnection con = repo.getConnection(); try { String queryString = "PREFIX rk:
" + "SELECT ?s ?o " + "WHERE { " + "?s rk:type rk:CreativeWork ." + "?s ?p ?o ." + "} "; TupleQuery tupleQuery = con.prepareTupleQuery(QueryLanguage.SPARQL, queryString); long startTime = System.currentTimeMillis(); TupleQueryResult result = tupleQuery.evaluate(); long secondTime = System.currentTimeMillis(); List
bindingNames = result.getBindingNames(); //get the name of binded variables while (result.hasNext()) { BindingSet bindingSet = result.next(); Value firstValue = bindingSet.getValue("s"); //bindingSet.getValue(bindingNames.get(0)); Value secondValue = bindingSet.getValue("o"); //bindingSet.getValue(bindingNames.get(1)); System.out.println(firstValue); System.out.println(secondValue); // do something interesting with the values here... } long endTime = System.currentTimeMillis(); System.out.println("evaluation time = "+(secondTime-startTime)); System.out.println("fetch time = "+(endTime-secondTime)); } finally { con.close(); }}catch (OpenRDFException e) { // handle exceptione.printStackTrace();}}
2. modify data
public static void updateQuery() {String updateQuery = "PREFIX rk:
" +"DELETE { " +"?creativeWork rk:type ?type ." +"} " +"INSERT { " +"?creativeWork rk:type ?typeUri ." +"} " +"WHERE { " +"?creativeWork rk:type ?type ." +"BIND( URI(?type) AS ?typeUri ) " +"} ";RepositoryConnection conn;try {conn = repo.getConnection();Update update = conn.prepareUpdate(QueryLanguage.SPARQL, updateQuery);update.execute();conn.commit();conn.close();} catch (RepositoryException e) {e.printStackTrace();} catch (MalformedQueryException e) {e.printStackTrace();} catch (UpdateExecutionException e) {e.printStackTrace();}}
For more information about the SPARQL language, see Learning SPARQL.