[Zope] zope:change strings on place

Can you help me ? I have some dates in a DataBase but I receive them in string after a query and it's in international format, I would like transform it in french format. With <dtml-var date fmt=%d%m%y>, it doesn't work. Do you know how can I transform it with strings: I receive : 2000-04-13 I want : 13-04-2000 or : 13 april 2000 (this one is better but ???) I thanks you a lot, please help me. Vincent.