SELECT
group_concat( `tf_business_goods_info`.`id` ORDER BY cast( `tf_business_goods_info`.`original_price` AS DECIMAL (10, 2) ) ASC SEPARATOR ',' ) FROM `tf_business_goods_info` GROUP BY `tf_business_goods_info`.`master_id`
就是根据分组把这个一行展示出来
取第几个