Top 3 items of each group

gistfile1.sql

select cat.name, sub.name, x.name, x.price, x.qty from product_categories cat
  left join product_categories sub on cat.id = sub.product_category_id
  left OUTER JOIN (
    SELECT a.*
    FROM products a
      LEFT JOIN products b ON a.product_category_id = b.product_category_id AND a.id <= b.id
    GROUP BY a.name
    HAVING count(*) <= 3
    ORDER BY a.product_category_id
    ) x on x.product_category_id = sub.id;