PostgreSQL | PGExercises.com | Rank users by total hours

-- https://pgexercises.com/questions/aggregates/rankmembers.html

with t1 as (
    select firstname, surname, ROUND(sum(slots/2.0),-1) as hours
    -- round(x,-1) rounds x to nearest 10, https://stackoverflow.com/a/41210389
    from cd.bookings b
    join cd.members m
    on b.memid = m.memid
    group by 1, 2
    order by 3 desc, 2 asc, 1 asc
)
select *, rank() over(order by hours desc)
from t1