I have used Data class and found some mismatch of date usage. How to solve this?

in pHP: date("Y-m-d"): gives 2008-02-23
in zf : $date->toString("Y-m-d"); give 2008-i-23 like that. Time also coming like that . how to solve this and how to take the time 05:25:04 and date 2008-02-25?

- mugesh