WITH DIF AS(
SELECT
    USER_ID
    ,TEST_ID
    ,POINT AS PT
    ,POINT - (SELECT AVG(POINT) FROM TEST_RESULTS) AS DIFF
FROM
    TEST_RESULTS
WHERE
    TEST_ID = '100'
)
,STDE AS(
SELECT
    USER_ID
    ,PT
    ,SQRT(AVG(DIFF*DIFF) OVER()) AS STD
FROM
    DIF
)
SELECT
    USER_ID
    ,PT
    ,ROUND(10*(PT - (SELECT AVG(POINT) FROM TEST_RESULTS))/STD + 50,1) AS DEV_VAL
FROM
    STDE
ORDER BY
    DEV_VAL DESC
    ,USER_ID ASC
;