add new location field

location of the DVD (room/box/case/etc)

locations table
===============
loc_id - primary key
parent_id - foreign key to locations.loc_id (same table) (NULLable)
name - varchar

+case 1 (loc_id=1, parent_id=NULL)
| |
| |________box1 (loc_id=2, parent_id=1)
| | |
| | |_______foo (loc_id=5, parent_id=2)
| | |
| | |_______bar (loc_id=6, parent_id=2)
| |
| |________baz (loc_id=7, parent_id=1)
|
+room a (loc_id=3, parent_id=NULL)
|
+my_box (loc_id=8, parent_id=NULL)
  |
  |________foo (loc_id=9, parent_id=8)

movies table
============
movie_id - primary key
loc_id - foreign key to locations.loc_id (NULLable)

fetching location in app.
=========================
location = []
if movie.location:
   location = [movie.location.name]

   i = movie.location.parent

   while i.parent:
       location.append(i.parent.name)
       i = i.parent
location_str = ' / '.join(location[::-1])
# returns f.e. "case 1 / box1 / foo"