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Alexander Koblov · Aug 18, 2021

InterSystems IRIS does not have a MEDIAN SQL function. However, it has different window functions.

For example, Percent_Rank might help you here.

create table test(c1 varchar(10), c2 integer)

insert into test(c1,c2) 
select 'a',1
union all
select 'b',2
union all
select 'c',3
union all
select 'd',3
union all
select 'e',3
union all
select 'f',4
union all
select 'g',5
union all
select 'h',6

select c1, c2, Percent_Rank () OVER ( 
    ORDER BY c2 desc
) rank_no 

from test
order by c2 desc

c1  c2  rank_no
h   6   0
g   5   .1428571428571428571
f   4   .2857142857142857143
c   3   .4285714285714285714
d   3   .4285714285714285714
e   3   .4285714285714285714
b   2   .8571428571428571429
a   1   1

Doc: https://docs.intersystems.com/irislatest/csp/docbook/Doc.View.cls?KEY=RS...

Also, it's possible to create a user-defined aggregate function. See https://docs.intersystems.com/irislatest/csp/docbook/DocBook.UI.Page.cls...

3 0
Randy Shaw · Aug 17, 2021

I happened to need Median recently and came up with this solution.

SELECT TOP 1
    AVG(main.age) AS _Average,min(main.age) AS _Min,
    CASE WHEN %vid = count(main.age)/2 THEN main.age else 0 END+MAX(CASE WHEN %vid = count(main.age)/2 THEN main.age else 0 END) AS  _Median,
    max(main.age) AS _Max
FROM
(
SELECT TOP all a.Age FROM Sample.Person a
ORDER BY a.Age
) main
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