code: @Override
      public int append2SQLSelect(final Type _type,
                                  final SQLSelect _select,
                                  final int _tableIndex,
                                  final int _colIndex)
      {
          int ret = 0;
          if (getParent() == null || !"type".equals(getParent().getValueType())) {
              this.type = _type;
              _select.column(_tableIndex, "ID");
              getColIndexs().add(_colIndex);
              ret++;
          }
          // in case that the type has a column for type it must be added
          if (this.type != null) {
              if (this.type.getMainTable().getSqlColType() != null) {
                  _select.column(_tableIndex, this.type.getMainTable().getSqlColType());
                  getColIndexs().add(_colIndex + ret);
                  ret++;
              }
          }
          this.attribute = _type.getAttribute("OID");
          return ret;
      }
docs: {@inheritDoc}