Prepared statements and default values

I have a preparedStatement with the following query
 "UPDATE usersettings SET gpsfrequency = ? , serverurl = ? where
username = ? ;";

In the db, the table userSettings has a default value specified for
gps_frequency .

So when I write code
if (client.getSettings().getField(Settings.GPS_FREQUENCY).compareTo(""))==0)
    <what goes here> //pick up the default value from the db.
else
    setUserSettings.setInt(++i,
Integer.parseInt(client.getSettings().getField(Settings.GPS_FREQUENCY)));


<what goes here> .. I basically want to send something that lets the
db know to use the DEFAULT value. (its of type int0)

So what does go here?

any help would be much appreciated.

-a