如何将我的前5名工资和后5名工资结合起来在Oracle中显示？

Posted 2021-04-04

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;

答案

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;