code: @Override
      public void prepare(final AbstractSQLInsertUpdate<?> _insertUpdate,
                          final Attribute _attribute,
                          final Object... _values)
          throws SQLException
      {
          checkSQLColumnSize(_attribute, 2);
          final Rate value = eval(_values);
          _insertUpdate.column(_attribute.getSqlColNames().get(0), value.getNumerator());
          _insertUpdate.column(_attribute.getSqlColNames().get(1), value.getDenominator());
      }
docs: The method prepares the statement for insert the object in the database.
  It must be overwritten, because this type has at least two columns.
  {@inheritDoc}