--q76.sql--

 SELECT
    channel, col_name, d_year, d_qoy, i_category, COUNT(*) sales_cnt,
    SUM(ext_sales_price) sales_amt
 FROM(
    SELECT
        'store' as channel, ss_store_sk col_name, d_year, d_qoy, i_category,
        ss_ext_sales_price ext_sales_price
    FROM store_sales, item, date_dim
    WHERE ss_store_sk IS NULL
      AND ss_sold_date_sk=d_date_sk
      AND ss_item_sk=i_item_sk
    UNION ALL
    SELECT
        'web' as channel, ws_ship_customer_sk col_name, d_year, d_qoy, i_category,
        ws_ext_sales_price ext_sales_price
    FROM web_sales, item, date_dim
    WHERE ws_ship_customer_sk IS NULL
      AND ws_sold_date_sk=d_date_sk
      AND ws_item_sk=i_item_sk
    UNION ALL
    SELECT
        'catalog' as channel, cs_ship_addr_sk col_name, d_year, d_qoy, i_category,
        cs_ext_sales_price ext_sales_price
    FROM catalog_sales, item, date_dim
    WHERE cs_ship_addr_sk IS NULL
      AND cs_sold_date_sk=d_date_sk
      AND cs_item_sk=i_item_sk) foo
 GROUP BY channel, col_name, d_year, d_qoy, i_category
 ORDER BY channel, col_name, d_year, d_qoy, i_category
 limit 100