code: protected boolean executeOneCompleteStmt(final String _complStmt,
                                               final List<Instance> _instances)
          throws EFapsException
      {
          final boolean ret = false;
          ConnectionResource con = null;
          try {
              con = Context.getThreadContext().getConnectionResource();
  
              final Statement stmt = con.createStatement();
  
              final ResultSet rs = stmt.executeQuery(_complStmt.toString());
              final Map<Long, List<Long>> link2clazz = new HashMap<>();
              while (rs.next()) {
                  final long linkId = rs.getLong(2);
                  final long classificationID = rs.getLong(3);
                  final List<Long> templ;
                  if (link2clazz.containsKey(linkId)) {
                      templ = link2clazz.get(linkId);
                  } else {
                      templ = new ArrayList<>();
                      link2clazz.put(linkId, templ);
                  }
                  templ.add(classificationID);
              }
              for (final Instance instance : _instances) {
                  this.instances2classId.put(instance, link2clazz.get(instance.getId()));
              }
              rs.close();
              stmt.close();
          } catch (final SQLException e) {
              throw new EFapsException(ClassificationValueSelect.class, "executeOneCompleteStmt", e);
          }
          return ret;
      }
docs: Method to execute one statement against the eFaps-DataBase.
  
  @param _complStmt ststement
  @param _instances list of instances
  @return true it values where found
  @throws EFapsException on error