How do I combine both my top 5 salaries and bottom

Question

So I know how to get the top 5 and bottom 5 to display by themselves. Problem is how do I combine both to display at the same time. This is what I have but it only shows the bottom 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;

Answer 1

Use UNION or 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;

You can also write this more succinctly as:

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;