WITH TMP(USER_ID, POINT) AS (
    SELECT USER_ID, POINT
    FROM TEST_RESULTS
    WHERE TEST_ID = '100'
),
X_ AS (SELECT AVG(POINT) FROM TMP),
STDEV AS (
    SELECT SQRT(AVG(POWER(POINT - (SELECT * FROM X_), 2)))
    FROM TMP
)
SELECT
    USER_ID USER,
    POINT PT,
    ROUND(CASE WHEN (SELECT * FROM STDEV) = 0 THEN 50 ELSE (POINT - (SELECT * FROM X_)) * 10 / (SELECT * FROM STDEV) + 50 END, 1) DEV_VAL
FROM TMP
ORDER BY DEV_VAL DESC, USER_ID ASC