WITH
mean AS (
  SELECT AVG(POINT) AS AVG_POINT
  FROM TEST_RESULTS
  WHERE TEST_ID = '100'
),
variance AS (
  SELECT AVG((POINT - mean.AVG_POINT) * (POINT - mean.AVG_POINT)) AS VAR_POINT
  FROM TEST_RESULTS, mean
  WHERE TEST_ID = '100'
),
std_dev AS (
  SELECT SQRT(VAR_POINT) AS STD_POINT
  FROM variance
)
SELECT
  USER_ID AS USER,
  POINT AS PT,
  ROUND(
    CASE 
      WHEN STD_POINT = 0 THEN 50
      ELSE 50 + 10 * (POINT - mean.AVG_POINT) / STD_POINT
    END, 2
  ) AS DEV_VAL
FROM TEST_RESULTS, mean, std_dev
WHERE TEST_ID = '100'
ORDER BY DEV_VAL DESC, USER ASC;