How to get previous row of result set in select query?

Question

I want to access the previous row of an result set obtained yet, in the same selectquery .
How can I do that?

Answer 1

Use analytical functions.
For example:
create table top_n_test (
   a number,
   b varchar2(10)
insert into top_n_test values (1,   'one');
insert into top_n_test values (2,   'two');
insert into top_n_test values (3, 'three');
insert into top_n_test values (4,  'four');
insert into top_n_test values (5,  'five');
insert into top_n_test values (6,   'six');
insert into top_n_test values (7, 'seven');
insert into top_n_test values (8, 'eight');
insert into top_n_test values (9,  'nine');
commit;
select a, b from (
  select
    a,b,
    rank() over (order by b) r
  from
    top_n_test
where
  r<4;
         A B
         8 eight
         5 five
         4 fourHTH
Ghulam