Subdirectory backend

[Magiccupcake]

I am trying to figure out a way to create a directory with a backend where all the links will be saved in a database and then they would be able to be sorted into subcategories.

so if in the directory was

a
b
c
d
e
f
g
h
i

They could be sorted to display like

a
- b
- c
-- e
- d
f
- g
-- h
--- i

so links 'a' and 'f' would show. if link 'a' was clicked 'b' and 'c' would show. and so on.

I am not looking for code or anything, just an idea of how to do it.

Thanks.