WITH T AS

(

SELECT 20 AS DATA1, 2 AS DATA2 FROM DUAL

UNION ALL SELECT 30, 3 FROM DUAL

UNION ALL SELECT 40, 4 FROM DUAL

)

SELECT STDDEV(DATA1), STDDEV(DATA2)

FROM T

위의 20, 2, 30, 3, 40, 4 의 표준편차를 구해야하는데

이상한 값이 나오더라고요.

WITH T AS

(

SELECT 20 AS DATA1 FROM DUAL

UNION ALL SELECT 30 FROM DUAL

UNION ALL SELECT 40 FROM DUAL

UNION ALL SELECT 2 FROM DUAL

UNION ALL SELECT 3 FROM DUAL

UNION ALL SELECT 4 FROM DUAL

)

SELECT STDDEV(DATA1)

FROM T

위와같이 테이블 구조를 변경해서 하면 값이 잘 나오는데

좋은 방법이 있을까요?