Пишу ИС еще один сайт о информационных системах

WITH RECURSIVE sub_category(code, name, parent_code, level) AS (
	SELECT code, name, parent_code, 1 FROM goods_category WHERE code=5 /* код узла */
	UNION ALL 
	SELECT c.code, c.name, c.parent_code, level+1
	FROM goods_category c, sub_category sc
	WHERE c.code = sc.parent_code  
)
SELECT code, name, parent_code, (SELECT max(level) FROM sub_category) - level AS distance FROM sub_category;