WITH AVG as (
SELECT
 AVG(POINT) as AVG
FROM TEST_RESULTS
WHERE TEST_ID = '100'
),

DIF as (
  SELECT
  SQRT(
    AVG((T.POINT - AVG.AVG) * (T.POINT - AVG.AVG)
      )) as STANDARD_DEVIATION
  FROM TEST_RESULTS as T
  CROSS JOIN AVG
  WHERE TEST_ID = '100'
)

SELECT
  USER_ID as USER,
  POINT as PT,
  CASE WHEN STANDARD_DEVIATION <> 0 THEN 
    ROUND((((POINT - AVG) * 10) / STANDARD_DEVIATION),1) + 50 
  ELSE 50 END  as DEV_VAL
FROM TEST_RESULTS
CROSS JOIN AVG 
CROSS JOIN DIF
WHERE TEST_ID = '100'
ORDER BY DEV_VAL desc,USER asc