select round(count(distinct D.user_id)/count(distinct C.user_id),3) as p
from 
login C
left join
(select A.id,A.user_id,A.client_id,A.date
from login A
LEFT JOIN
login B
on A.user_id = B.user_id
where year(A.date) = year(B.date) 
and month(A.date) = month(B.date)
and day(A.date) + 1  =  day(B.date)) as D
on C.id = D.id