with visit as(
select date(visit_time) visit_day
,count(distinct user_id) visit_uv
from visit_tb
group by 1
)

,orders as(
select date(order_time) order_day
,count(distinct user_id) order_uv
from order_tb
group by 1
)

select visit_day date
,case when visit_day = 0 then 0
else concat(round(order_uv/visit_uv*100,1),'%') end  cr
from visit
left join orders
on visit_day = order_day