foo.py

#!/usr/bin/env python

import os.path

dir = os.path.dirname(__file__)
db = os.path.join(dir, 'foobar.sqlite')

print __file__
print dir
print db

$ python2.7 /tmp/foo.py
/tmp/foo.py
/tmp
/tmp/foobar.sqlite

$ cd /tmp
$ python2.7 ./foo.py  
./foo.py        
.
./foobar.sqlite

usw.