docs: public void combine(SearchFilter new_filter, int op) throws DBException
      {
  
          // cast down to OJBSearchFilter
          OJBSearchFilter ojbFilter = (OJBSearchFilter) new_filter;
  
          switch (op)
          {
  
              case OR:
                  {
                      criteria.addOrCriteria(ojbFilter.getCriteria());
                      break;
                  }
  
              case AND:
                  {
                      criteria.addAndCriteria(ojbFilter.getCriteria());
                      break;
                  }
  
              default:
                  {
                      throw new DBException();
                  }
          }
      }