WITH
BASE AS(
    SELECT * FROM TEST_RESULTS WHERE TEST_ID = '100'
),
T1 AS(
	SELECT AVG(POINT) AS AVG_POINT FROM BASE
),
T2 AS( -- 分散
	SELECT
		SQRT(
			AVG(
				POW(POINT - (SELECT AVG_POINT FROM T1), 2)
			)
		) AS HENSA
	FROM
		BASE
)
SELECT
	USER_ID AS USER
	, POINT AS PT
	, ROUND(
	    CASE (SELECT HENSA FROM T2) 
    	    WHEN 0 THEN 50 
    	    ELSE (POINT - (SELECT AVG_POINT FROM T1)) * 10 / (SELECT HENSA FROM T2) + 50
	    END, 2)  AS DEV_VAL
FROM
	BASE
ORDER BY
	DEV_VAL DESC
	, USER_ID