how to use datalist control in case Category Table

create table categories
( id       integer     not null  primary key
, name     varchar(37) not null
, parentid integer     null
, foreign key parentid_fk (parentid)
      references categories (id)
);

id	name	parentid
1	animal	NULL
2	vegetable	NULL
3	mineral	NULL
4	doggie	1
5	kittie	1
6	horsie	1
7	gerbil	1
8	birdie	1
9	carrot	2
10	tomato	2
11	potato	2
12	celery	2
13	rutabaga	2
14	quartz	3
15	feldspar	3
16	silica	3
17	gypsum	3
18	hunting	4
19	companion	4
20	herding	4
21	setter	18
22	pointer	18
23	terrier	18
24	poodle	19
25	chihuahua	19
26	shepherd	20
27	collie	20