Top 5 and Bottom 5

Question

Hi all ,
Can anyone help me in solving the following problem ..
How to get top 5 and bottom 5 selling books in a single query
Eg:
Book name No.sold
A 45
B 78
C 8
D 6
T 66
E 33
AA 35
AB 95
AC 51
AD 5
AE 42
desired output :
Top 5 bname | bottom 5 bname
AB AD
B D
T C
AC E
A AA
Thanks in advance
Sana

Answer 1

Since, in general, more than one book can have same no_sold, more than 5 books can have top/bottom no_sold. If you want all 5 top and bottom selling books, use:
with t as (
           select  book_name,
                   no_sold,
                   dense_rank() over (order by no_sold desc) rnk_top,
                   dense_rank() over (order by no_sold) rnk_bottom,
                   row_number() over (order by no_sold desc) rn_top,
                   row_number() over (order by no_sold) rn_bottom
             from  books
select  t1.book_name,
        t2.book_name,
        t1.no_sold top_no_sold,
        t2.no_sold bottom_no_sold,
        nvl(t1.rnk_top,t2.rnk_bottom) rank
  from      t t1
        full join
            t t2
          on (
                  t2.rn_bottom = t1.rn_top
  where t1.rnk_top <= 5
    and t2.rnk_bottom <= 5
  order by nvl(t1.rn_top,t2.rn_bottom)
BO BO TOP_NO_SOLD BOTTOM_NO_SOLD       RANK
AB AD          95              5          1
B  D           78              6          2
T  C           66              8          3
AC E           51             33          4
A  AA          45             35          5
SQL> If all you want is any 5 top/bottom sold books:
with t as (
           select  book_name,
                   no_sold,
                   row_number() over (order by no_sold desc) rn_top,
                   row_number() over (order by no_sold) rn_bottom
             from  books
select  t1.book_name,
        t2.book_name,
        t1.no_sold top_no_sold,
        t2.no_sold bottom_no_sold,
        t1.rn_top rn
  from      t t1
        inner join
            t t2
          on (
                  t1.rn_top <= 5
              and
                  t2.rn_bottom <= 5
              and
                  t2.rn_bottom = t1.rn_top
  order by rn
BO BO TOP_NO_SOLD BOTTOM_NO_SOLD         RN
AB AD          95              5          1
B  D           78              6          2
T  C           66              8          3
AC E           51             33          4
A  AA          45             35          5
SQL> SY.