select product_id,round(sum(if_click)/count(1),3) as ctr,
round(if(sum(if_click)!=0,sum(if_cart)/sum(if_click),0),3) as cart_rate,
round(if(sum(if_cart)!=0,sum(if_payment)/sum(if_cart),0),3) as payment_rate,
round(if(sum(if_payment)!=0,sum(if_refund)/sum(if_payment),0),3) as 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