Date format

Hi, I have some doubts as date  format is displayed is 2013-07-25  yy/mm/dd, as it is in database.

1-How/is it possible to format dd/mm/yy in database ?

2-How to format dd/mm/yy in HTML.

3- Is it right to format it dd/mm/yy  in database, or is it mandatory it to be  yy/mm/dd and being formated at display moment ?

Regards

Moises