Question

Given a table with multiple rows of an int field and the same identifier, is it possible to return the 2nd maximum and 2nd minimum value from the table.

A table consists of

ID      |   number
------------------------
1       |     10
1       |     11
1       |     13
1       |     14
1       |     15
1       |     16

Final Result would be

ID      |   nMin    |   nMax
--------------------------------
1       |     11    |    15

Answer 1

You can use row_number to assign a ranking per ID. Then you can group by id and pick the rows with the ranking you’re after. The following example picks the second lowest and third highest :

select  id
,       max(case when rnAsc = 2 then number end) as SecondLowest
,       max(case when rnDesc = 3 then number end) as ThirdHighest
from    (
        select  ID
        ,       row_number() over (partition by ID order by number) as rnAsc
        ,       row_number() over (partition by ID order by number desc) as rnDesc
        ) as SubQueryAlias
group by
        id

The max is just to pick out the one non-null value; you can replace it with min or even avg and it would not affect the outcome.