First 2 Higher Number and Last 2 Lower Number

Question

Hi Experts
I have a table with the name T there are some numeric values i want to select First 2(60, 50) Higher numbers and Last 2 (10 and 20) Lower numbers with query.
I'm using Oracle 10g R2
C1
     10
     20
     30
     40
     50
     60
Please help me in this regard
Regards,
Nasir.

Answer 1

With this solution you scan your table one time.
REgards Salim.
select c1
from (
            select c1,find
            from t
            model
            dimension by ( row_number()over(partition by 1 order by c1) rn)
              measures( c1, 0 find, count(1)over(partition by 1) cpt)
             ( find[any]= case when cv(rn) in (1,2,cpt[1],cpt[1]-1) then 1 else 0 end )
where find=1
SQL> with t  as ( select        10 C1 from dual union all
  2   select 20  from dual union all
  3   select 30 from dual union all
  4   select 40 from dual union all
  5   select 50 from dual union all
  6   select 60 from dual )
  7  select c1
  8  from (
  9              select c1,find
10              from t
11              model
12              dimension by ( row_number()over(partition by 1 order by c1) rn)
13                measures( c1, 0 find, count(1)over(partition by 1) cpt)
14               ( find[any]= case when cv(rn) in (1,2,cpt[1],cpt[1]-1) then 1 else 0 end )
15          )
16  where find=1
17  /
        C1
        10
        20
        50
        60
SQL>