题解 | #2021年10月退货率不大于0.5的商品指标#

select
    product_id,
    if (
        count(*) = 0,
        0, 
        round(sum(if_click) / count(*),3)) ctr,
    if (
        sum(if_click) = 0,
        0,
        round(sum(if_cart) / sum(if_click),3)
    ) cart_rate,
    if (
        sum(if_cart) = 0,
        0,
        round(sum(if_payment) / sum(if_cart),3)
    ) payment_rate,
    if (
        sum(if_payment) = 0,
        0,
        round(sum(if_refund) / sum(if_payment),3)
    ) refund_rate
from
    tb_user_event
where 
    month(event_time) = 10
group by
    product_id
order by 
    product_id

本题不难主要是考量一个聚合函数的除法计算，还得在if条件中判断分母是否为0，代码如上