DELETE FROM TEST_RESULTS WHERE TEST_ID <> 100;

WITH SUB AS (
    SELECT SQRT(AVG(D)) AS S
    FROM (
        SELECT POWER(POINT - (SELECT AVG(POINT) FROM TEST_RESULTS), 2) AS D FROM TEST_RESULTS
    )
)

SELECT USER_ID AS USER, POINT AS PT, CASE WHEN S = 0 THEN 50 ELSE ROUND((POINT - (SELECT AVG(POINT) FROM TEST_RESULTS)) * 10 / S + 50, 1) END AS DEV_VAL
FROM TEST_RESULTS CROSS JOIN SUB
ORDER BY DEV_VAL DESC, USER;