Selection Screen - Date and Time

Hi,

I have given a selection screen where the user needs to key in the input in the following format

dd.mm.yyyy hh:mm:ss.

Reason is that the database fetching these elements accepts only in this criteria.

Now as they look into automating this program, they would want to automatically take the current system date and time - 24 hours .

How do I achieve this in the above format? If this is not possible, let me know if i can make the selection screen with normal sap date format and convert it to the above format on passing to the select statement.

Regards

Sam