あなたはこれを探していると思います：
select Distinct * from（SELECT date、if（group_concat（distinct cust_price）、from_product_id、null）as from_product_id、if（group_concat（distinct comp_price）、to_product_id、null）as to_product_id、group_concat（distinct cust_price）as cust_price、group_concat（distinct comp_price）as comp_price FROM（select cust_hist.date、matches.from_product_id、matches.to_product_id、cust_hist.price cust_price、comp_hist.price comp_price from tmp_match matches inner join tmp_price_history cust_hist on matches.from_product_id =cust_ tmp_price_history comp_hist on matches.to_product_id =comp_hist.product_id WHERE comp_hist.date =cust_hist.date union select comp_hist.date、matches.from_product_id、matches.to_produc t_id、null as cust_price、comp_hist.price comp_price from tmp_price_history comp_hist join tmp_match matchs on matches.to_product_id =comp_hist.product_id＃and matches.from_product_id is null union select cust_hist.date、matches.from_product_id、matches.to_product_id、cust_hist.price null comp_price from tmp_price_history cust_hist join tmp_match matchs on matches.from_product_id =cust_hist.product_id＃and matches.to_product_id is null order by DATE、from_product_id、to_product_id、cust_price、comp_price）as u group by date、from_product_id、to_product_id）gSQLスニペットについてのあなたのアイデアは素晴らしかったです！