Jena Update Syntax

import com.hp.hpl.jena.rdf.model.Model;
import com.hp.hpl.jena.rdf.model.ModelFactory;
import com.hp.hpl.jena.rdf.model.RDFWriter;
import com.hp.hpl.jena.update.UpdateAction;
import com.hp.hpl.jena.update.UpdateFactory;
import com.hp.hpl.jena.update.UpdateRequest;

public class UpdateTest
{
    public static void main(String[] args)
    {
        Model model = ModelFactory.createDefaultModel();
        model.read("http://purl.org/hcls/2007/kb-sources/addgene.ttl", "N3");
        RDFWriter writer = model.getWriter("N3");
        System.out.println("# before update");
        writer.write(model, System.out, "");

        String query =
            "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> " +
            "INSERT {" +
            "  ?s rdfs:comment \"added by Jena\" " +
            "} WHERE {" +
            "  ?s rdfs:label ?label " +
            "}";
        UpdateRequest request = UpdateFactory.create(query);
        UpdateAction.execute(request, model);
        System.out.println("# after update");
        writer.write(model, System.out, "");
    }
}