with sub as (
    select avg(point) as average
    from TEST_RESULTS
    where test_id='100'
),
sub2 as (
    select
        sqrt(avg((t.point-sub.average)*(t.point-sub.average))) as stdd
    from test_results t
    cross join sub
    where test_id='100'
)
select 
    user_id as USER
    , POINT as PT
    , case when stdd <> 0 then round(((point-average)*10)/stdd,1)+50 else 50 end as DEV_VAL
from test_results
    cross join sub
    cross join sub2
where test_id='100'
order by dev_val desc, user_id asc;