DELETE FROM TEST_RESULTS WHERE TEST_ID <> '100';

SELECT USER_ID AS USER, POINT AS PT, CASE WHEN (
    SELECT SQRT(AVG(DIFF_SQUARE))
    FROM (
        SELECT POWER(POINT - (SELECT AVG(POINT) FROM TEST_RESULTS), 2) AS DIFF_SQUARE FROM TEST_RESULTS
    )
) = 0 THEN 50 ELSE 
ROUND((POINT - (SELECT AVG(POINT) FROM TEST_RESULTS)) * 10 / 
(
    SELECT SQRT(AVG(DIFF_SQUARE))
    FROM (
        SELECT POWER(POINT - (SELECT AVG(POINT) FROM TEST_RESULTS), 2) AS DIFF_SQUARE FROM TEST_RESULTS
    )
) + 50, 1) END AS DEV_VAL
FROM TEST_RESULTS
ORDER BY DEV_VAL DESC, USER;