LIMIT between some column

Hi!

My query is

SELECT id_category,name FROM categories WHERE level BETWEEN 1
AND 2 AND lft>1 AND rgt<100 AND active=true ORDER BY name

This is about 30 or more records. This records can be grouped
by id_parent. What i want to do is limit data in a way that i
could get for example only 3 or 4 records with same
id_parent.

here is some data for explanation.

id    |    parent    |
0     |              |
1     |       0      |
2     |       0      |
3     |       0      |
4     |       0      |
5     |       1      |
6     |       1      |
7     |       1      |
8     |       1      |
9     |       2      |
10    |       2      |
11    |       3      |
12    |       4      |
13    |       4      |
14    |       4      |
15    |       4      |
16    |       4      |

When i execute my query i get all ids from 5 to 16, but i
want it to limit somehow that i get only ids,
5,6,7,9,10,11,12,13,14. I hope my problem is understandable.
Do I have to use join on table itself or how.

--
lp,
 Uros                          mailto:uros@sir-mag.com