select product_id, #先判断分母是否为0,是0结果就是0,不是再利用分子除以分母,并且利用round对结果进行设置格式 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(...