SELECT USER_ID AS USER
,POINT AS PT
,ROUND((POINT-AVP)*10/S+50,1) AS DEV_VAL
FROM TEST_RESULTS
JOIN (
SELECT 
ROUND(SQRT(CAST(SUM(POWER(POINT-AVP,2)) AS REAL)/CNT),1) AS S
,AVP
,CNT
FROM TEST_RESULTS
JOIN (SELECT AVG(POINT) AVP,COUNT(*) CNT FROM TEST_RESULTS)
WHERE TEST_ID = '100')
WHERE TEST_ID = '100'
ORDER BY DEV_VAL DESC,USER_ID