category & sub category

Hi I have table where i want to display the categories with parent id 0 and When parent id is 1 or 2 and so on...

it should display as :

autos/auto1
autos/cars

Etc:

My database table is like this:

cid int(11) No auto_increment
parentid int(11) No 0
img varchar(30) latin1_swedish_ci No
title varchar(40) latin1_swedish_ci No
cdesc text latin1_swedish_ci No
hits

Currently it is diaplying straight as:

categories
and after finish of main categories .

sub ategories start.

i am using the query as;

select cid, title, parentid
from grcat
order by cid

<cfselect name="category" label="Select Category: " value="cid" display="title" query="getCats" tabindex="1" tooltip="Chooose Your category"></cfselect>

i want is my subcategories should show after their maincategory

like:

autos/car
autos/files

in the same single select.

I trying it but no possible solution working me instead