WITH T1 AS (
SELECT AVG(POINT) AS AVE
FROM TEST_RESULTS
WHERE TEST_ID='100'
),T2 AS (
SELECT AVE,ROUND(SQRT(AVG((POINT-AVE)*(POINT-AVE))),1) AS STDEV
FROM TEST_RESULTS AS TEST CROSS JOIN T1
WHERE TEST_ID='100'
)
SELECT USER_ID USER,POINT PT,CASE WHEN STDEV=0 THEN 50 ELSE ROUND((POINT-AVE)*10/STDEV,1) + 50 END AS DEV_VAL
FROM TEST_RESULTS AS TEST CROSS JOIN T2
WHERE TEST_ID='100'
ORDER BY DEV_VAL DESC,USER_ID