with a as (
select
    *,
    p2-p1*p1 as v,
    sqrt(p2-p1*p1) as std
from
(
        select
            cast(sum(POINT) as real) / cast(count(*) as real) p1,
            cast(sum(POINT * POINT) as real) / cast(count(*) as real) p2
        from
            TEST_RESULTS
        where
            TEST_ID = '100'
    ))
select 
USER_ID USER,
point PT,
round((cast(point as real)-p1)*10.0/std + 50,1)  DEV_VAL
 from
TEST_RESULTS,a
where test_id='100'
order by 3 desc,1