--q36.sql--

 select
    sum(ss_net_profit)/sum(ss_ext_sales_price) as gross_margin
   ,i_category
   ,i_class
   ,grouping(i_category)+grouping(i_class) as lochierarchy
   ,rank() over (
 	partition by grouping(i_category)+grouping(i_class),
 	case when grouping(i_class) = 0 then i_category end
 	order by sum(ss_net_profit)/sum(ss_ext_sales_price) asc) as rank_within_parent
 from
    store_sales, date_dim d1, item, store
 where
    d1.d_year = 2001
    and d1.d_date_sk = ss_sold_date_sk
    and i_item_sk  = ss_item_sk
    and s_store_sk  = ss_store_sk
    and s_state in ('TN','TN','TN','TN','TN','TN','TN','TN')
 group by rollup(i_category,i_class)
 order by
   lochierarchy desc
  ,case when lochierarchy = 0 then i_category end
  ,rank_within_parent
 limit 100