預設情況下可以對 DataObjects 進行排序
class SortDataObject extends DataObject {
    private static $db = array(
        'Name' => 'Varchar',
        'SortOrder' => 'Int'
    );
    
    private static $default_sort = 'SortOrder DESC';
}
class SortDataObject extends DataObject {
    private static $db = array(
        'Name' => 'Varchar',
        'SortOrder' => 'Int'
    );
    
    private static $default_sort = 'SortOrder DESC';
}