Keepassx database location

[Stephen Paul Lander]

Dear ubuntu-motu,
I have installed Keepassx on ubuntu 8.04 and keep a number of passwords
there. Using Keepassx, I then opened another keepass database (.kdb)
which was on a USB stick. That opened fine. However, Keepassx now cannot
find my original database. What is this original database called, and
where can I find it in the file system of ubuntu 8.04?
Thanks a lot for your help and kindest regards,
Steve Lander