text: 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;
  