with ex as (select 
avg(point) as p
, count(1) as cnt
from test_results where TEST_ID = '100'
)
, st as (select 
USER_ID, POINT, POINT - ex.p as diff
from test_results cross join ex where test_id = '100'
)
, si as (
select sqrt(avg(pow(diff, 2))) as sq
from st
)
select 
USER_ID as USER
, POINT as PT
, case when sq = 0 then 50 else ROUND(diff * 10 / sq + 50, 1) end as DEV_VAL
from st cross join si
order by DEV_VAL desc, USER_ID