WITH AVG_POINT as (
SELECT
    AVG(POINT) AVG_point
FROM
    TEST_RESULTS
WHERE
    TEST_ID = '100'
)
, STANDARD_DEVIATION as (
SELECT
    SQRT(AVG(POW(POINT - AVG_point,2))) standard_deviation
FROM
    TEST_RESULTS,
    AVG_POINT
WHERE
    TEST_ID = '100'
)
SELECT
    USER_ID USER,
    POINT PT,
    CASE
        WHEN standard_deviation <> 0 
            THEN ROUND((POINT - AVG_point)*10 / standard_deviation, 1) + 50
        ELSE 50
        END AS DEV_VAL
FROM
    TEST_RESULTS,
    AVG_POINT,
    standard_deviation
WHERE
    TEST_ID = '100'
ORDER BY
    DEV_VAL desc,
    USER
;