统计2021年10月每个退货率不大于0.5的商品各项指标

select
    product_id,
	-- 计算各个指标，注意判断分母为0的情况
    round(if (
        count(1) = 0, 0, sum(if_click) / count(1)
    ), 3) ctr,
    round(if (
        sum(if_click) = 0, 0, sum(if_cart) / sum(if_click)
    ), 3) cart_rate,
    round(if (
        sum(if_cart) = 0, 0, sum(if_payment) / sum(if_cart)
    ), 3) payment_rate,
    round(if (
        sum(if_payment) = 0, 0, sum(if_refund) / sum(if_payment)
    ), 3) refund_rate
from tb_user_event
where date_format(event_time,'%Y-%m') = '2021-10'
group by product_id
having refund_rate <= 0.5
order by product_id