with t1 as (
    select
        AVG(POINT) AS AVG_POINT
    from TEST_RESULTS
    where TEST_ID = '100'
),
t2 as (
    select
        POW(
            AVG(
                POW(POINT - AVG_POINT, 2)
            ), 
            0.5
        ) AS STDEV
    from TEST_RESULTS
    cross join t1
    where TEST_ID = '100'
)
select
    USER_ID as USER,
    POINT as PT,
    case
        when STDEV = 0 then 50
        else ROUND((POINT - AVG_POINT) * 10 / STDEV + 50, 1) 
    end as DEV_VAL
from TEST_RESULTS
cross join t1
cross join t2
where TEST_ID = '100'
order by DEV_VAL desc, USER