secondmax

How do I retrieve the second highest salary of emp?

There is no right or wrong treatment of duplicates, there are only buggy specifications…

There are plenty of ways to do this.

An Oracle 7 approach would be

SELECT MAX(SAL) 
FROM EMP, (
  SELECT MAX(SAL) MAXSAL FROM EMP) 
WHERE SAL>MAXSAL;

Using TOP-n queries I could use

 
SELECT SAL 
FROM (
  SELECT ROWNUM R,SAL FROM (
    SELECT SAL FROM EMP ORDER BY SAL DESC)) 
WHERE R=2;

Using ROW_NUMBER (or RANK or DENSE_RANK), I could use

SELECT SAL 
FROM (
  SELECT ROW_NUMBER() OVER (ORDER BY SAL DESC) R,SAL FROM EMP) 
WHERE R=2;

Another approach would be to create a SecondMax aggregate function, as the following example from the doc
Example 11-12 How to Create and Use a User-Defined Aggregate Function

SELECT SecondMax(sal)
FROM emp;

Ok, if I know I have 14 employees in EMP, retrieving the second highest is way easier 🙂

SELECT PERCENTILE_DISC(2/14) WITHIN GROUP (ORDER BY SAL DESC) 
FROM EMP;

12 thoughts on “secondmax”

radino July 11, 2008 at 07:11

I would not use RANK()..
SQL> SELECT ENAME, SAL FROM ( 2 SELECT ENAME, SAL FROM EMP ORDER BY SAL DESC) 3 WHERE ROWNUM < 5; ENAME SAL ---------- --------- KING 5000,00 SCOTT 3000,00 FORD 3000,00 JONES 2975,00 SQL> SQL> SQL> SELECT SAL 2 FROM ( 3 SELECT RANK() OVER (ORDER BY SAL DESC) R,SAL FROM EMP) 4 WHERE R=2;
SAL --------- 3000,00 3000,00 SQL> SQL> SQL> UPDATE EMP 2 SET SAL=5000 3 WHERE ENAME='JONES'; 1 row updated SQL> SQL> SQL> SELECT SAL 2 FROM ( 3 SELECT RANK() OVER (ORDER BY SAL DESC) R,SAL FROM EMP) 4 WHERE R=2; SAL --------- SQL> SQL> ROLLBACK;
Rollback complete
AketiJyuuzou July 16, 2008 at 12:56
My funny solution 😎

select RTrim(Ltrim(RegExp_Substr(XMLAgg(XMLElement(“dummy”,SAL) order by SAL desc),’…

[edit]
last part of query is missing due to < and wordpress, but it could be something like
```
RegExp_Substr(XMLAgg(XMLElement("dummy",SAL) order by SAL desc),'\d+',1,2)
```
[/edit]
AketiJyuuzou July 16, 2008 at 13:02

Oh, code-tag of my post was disable.

But I think that Laurent Schneider can understand my solution.

I got hint from this article which used group_concat of MySQL.
http://www.onlamp.com/pub/a/mysql/2007/03/29/emulating-analytic-aka-ranking-functions-with-mysql.html?page=4
Laurent Schneider Post authorJuly 16, 2008 at 13:34

no, I do not see your query but I could imagine something like

select RegExp_Substr( XMLAgg( XMLElement(SAL,SAL) order by SAL desc), '<.*?>.*?' ,1,2) FROM EMP;
Laurent Schneider Post authorJuly 16, 2008 at 13:51

Ok, let’s do it with XMLish functions 🙂

select extractvalue(XMLAgg(XMLElement(SAL,SAL) order by SAL desc),’/SAL[2]’) FROM EMP;

EXTRACTVALUE(XMLAGG(XMLELEMENT(SAL,SAL)ORDERBYSALDESC),’/SAL[2]’)
——————————————————————————–
3000
Laurent Schneider Post authorJuly 16, 2008 at 13:53

One more try to show what I learnt from Marco

select extractvalue(XMLAgg(XMLElement(SAL,SAL) order by SAL desc),’//SAL[2]/text()’) SAL FROM EMP

SAL
—-
3000
AketiJyuuzou July 16, 2008 at 14:48

Wow!!

greate solution.
I did not realize to use extractValue.
I will study XML.

In my old posts, my usage of code-tag was wrong.
My solution was below.

select RTrim(Ltrim( RegExp_Substr(XMLAgg(XMLElement("dummy",SAL) order by SAL desc),'>[^>]+<',1,2),'>'),'<') sal from scott.emp;

SAL
----
3000
Laurent Schneider Post authorJuly 16, 2008 at 15:39

me too, but XML is huge!!! good luck
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Aketi Jyuuzou September 1, 2009 at 22:48

Since 11gR2,
We can use nth_Value 😎

http://download.oracle.com/docs/cd/E11882_01/server.112/e10592/functions112.htm

select distinct
NTH_VALUE(sal,2)
over(order by sal desc Rows between Unbounded Preceding
and Unbounded Following)
from EMP;
Laurent Schneider September 2, 2009 at 08:24

sure, I thought about this too 🙂

I regret that nth value has no aggregate form. Distinct+analytic is a bit ugly…
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