所以我知道如何让前5名和后5名自己展示。问题是如何将两者结合起来同时显示。这就是我所拥有的,但它只显示了底部5。
SELECT SAL FROM
(
SELECT DISTINCT SAL FROM EMP WHERE SAL IS NOT NULL ORDER BY SAL DESC
)
WHERE ROWNUM <6 AND
SELECT SAL FROM
(
SELECT DISTINCT SAL FROM EMP WHERE SAL IS NOT NULL ORDER BY SAL ASC
)
WHERE ROWNUM <6;
使用UNION
或UNION ALL
:
SELECT SAL FROM
(
SELECT DISTINCT SAL FROM EMP WHERE SAL IS NOT NULL ORDER BY SAL DESC
)
WHERE ROWNUM < 6
UNION ALL
SELECT SAL FROM
(
SELECT DISTINCT SAL FROM EMP WHERE SAL IS NOT NULL ORDER BY SAL ASC
)
WHERE ROWNUM < 6;
你也可以更简洁地写这个:
SELECT SAL
FROM (SELECT DISTINCT SAL,
DENSE_RANK() OVER (ORDER BY sal) as seqnum_asc,
DENSE_RANK() OVER (ORDER BY sal) as seqnum_desc
FROM EMP
WHERE SAL IS NOT NULL
) s
WHERE seqnum_asc < 6 OR seqnum_desc < 6;