| WITH all_sales AS ( |
| SELECT |
| d_year, |
| i_brand_id, |
| i_class_id, |
| i_category_id, |
| i_manufact_id, |
| SUM(sales_cnt) AS sales_cnt, |
| SUM(sales_amt) AS sales_amt |
| FROM ( |
| SELECT |
| d_year, |
| i_brand_id, |
| i_class_id, |
| i_category_id, |
| i_manufact_id, |
| cs_quantity - COALESCE(cr_return_quantity, 0) AS sales_cnt, |
| cs_ext_sales_price - COALESCE(cr_return_amount, 0.0) AS sales_amt |
| FROM catalog_sales |
| JOIN item ON i_item_sk = cs_item_sk |
| JOIN date_dim ON d_date_sk = cs_sold_date_sk |
| LEFT JOIN catalog_returns ON (cs_order_number = cr_order_number |
| AND cs_item_sk = cr_item_sk) |
| WHERE i_category = 'Books' |
| UNION |
| SELECT |
| d_year, |
| i_brand_id, |
| i_class_id, |
| i_category_id, |
| i_manufact_id, |
| ss_quantity - COALESCE(sr_return_quantity, 0) AS sales_cnt, |
| ss_ext_sales_price - COALESCE(sr_return_amt, 0.0) AS sales_amt |
| FROM store_sales |
| JOIN item ON i_item_sk = ss_item_sk |
| JOIN date_dim ON d_date_sk = ss_sold_date_sk |
| LEFT JOIN store_returns ON (ss_ticket_number = sr_ticket_number |
| AND ss_item_sk = sr_item_sk) |
| WHERE i_category = 'Books' |
| UNION |
| SELECT |
| d_year, |
| i_brand_id, |
| i_class_id, |
| i_category_id, |
| i_manufact_id, |
| ws_quantity - COALESCE(wr_return_quantity, 0) AS sales_cnt, |
| ws_ext_sales_price - COALESCE(wr_return_amt, 0.0) AS sales_amt |
| FROM web_sales |
| JOIN item ON i_item_sk = ws_item_sk |
| JOIN date_dim ON d_date_sk = ws_sold_date_sk |
| LEFT JOIN web_returns ON (ws_order_number = wr_order_number |
| AND ws_item_sk = wr_item_sk) |
| WHERE i_category = 'Books') sales_detail |
| GROUP BY d_year, i_brand_id, i_class_id, i_category_id, i_manufact_id) |
| SELECT |
| prev_yr.d_year AS prev_year, |
| curr_yr.d_year AS `year`, |
| curr_yr.i_brand_id, |
| curr_yr.i_class_id, |
| curr_yr.i_category_id, |
| curr_yr.i_manufact_id, |
| prev_yr.sales_cnt AS prev_yr_cnt, |
| curr_yr.sales_cnt AS curr_yr_cnt, |
| curr_yr.sales_cnt - prev_yr.sales_cnt AS sales_cnt_diff, |
| curr_yr.sales_amt - prev_yr.sales_amt AS sales_amt_diff |
| FROM all_sales curr_yr, all_sales prev_yr |
| WHERE curr_yr.i_brand_id = prev_yr.i_brand_id |
| AND curr_yr.i_class_id = prev_yr.i_class_id |
| AND curr_yr.i_category_id = prev_yr.i_category_id |
| AND curr_yr.i_manufact_id = prev_yr.i_manufact_id |
| AND curr_yr.d_year = 2002 |
| AND prev_yr.d_year = 2002 - 1 |
| AND CAST(curr_yr.sales_cnt AS DECIMAL(17, 2)) / CAST(prev_yr.sales_cnt AS DECIMAL(17, 2)) < 0.9 |
| --ORDER BY sales_cnt_diff |
| --LIMIT 100 |