# 子查询 SELECT product_id, ROUND(IF(show_num > 0, click_num/ show_num, 0), 3) as ctr, ROUND(IF(click_num > 0, cart_num / click_num, 0 ), 3) as cart_rate, ROUND(IF(cart_num > 0, payment_num / cart_num, 0), 3) as payment_rate, ROUND(IF(payment_num > 0, refund_num / payment_num, 0), 3) as ref...