ShortTimeFormat?

Hi everybody,
I have got the problem that the standard display format for the time is hh:mm:ss.
I know that I can change it into hh:mm with the variable ShortTimeFormat, but I
don't know how? Has anybody got an idea? Second problem is that the database
also only accepts the hh:mm:ss format. I would like to change it also into hh:mm!

Thanx for your help.

Oliver Reu?