Child Parent

SELECT parent_vo_group_id, COUNT(parent_vo_group_id) Child_Count
FROM vo_group
WHERE PARENT_VO_GROUP_ID IN (SELECT VO_GROUP_ID FROM vo_group)
GROUP BY parent_vo_group_id
UNION
SELECT vog2.vo_group_id, vog2.parent_vo_group_id
FROM vo_group vog1, vo_group vog2
WHERE vog2.PARENT_VO_GROUP_ID = vog1.VO_GROUP_ID;