[Zope] sorting sql result

Hi folks! i have a sql statement that returns three fields, to be known: msg, author, forum_id. I would like to let me users to sort on them. My i have zope do that for me or i have to do it by myself into the sql statement? Which is the best approach (considering performance). Thanks for your help. -- Majority, n.: That quality that distinguishes a crime from a law.