WITH T3 AS (
SELECT AVG,
    SQRT(AVG(POW((POINT-AVG),2))) AS STDEV
FROM TEST_RESULTS AS T1
CROSS JOIN (
    SELECT USER_ID,
        AVG(POINT) AS 'AVG'
    FROM TEST_RESULTS
    WHERE TEST_ID='100'
) AS T2
WHERE T1.TEST_ID='100'
)
SELECT USER_ID AS USER,
    POINT AS PT,
    CASE STDEV WHEN 0 THEN 50 ELSE ROUND((POINT-AVG)*10/STDEV,1)+50 END AS DEV_VAL
FROM TEST_RESULTS CROSS JOIN T3
WHERE TEST_ID='100'
ORDER BY DEV_VAL DESC,USER_ID