Selecting consecutive two rows

Question

hi all,
i have a table 'sample' with following values
SAMPLE
COL1
1
1
2
2
2
3
3
4
4
6
6
6
In this column i need to display top two rows with their values...
wat i need exactly is shown below!!!!
Sample Output of my Query; When i run the query first time the query should give the following result
1
1
2
2
2
Similarly when i run the query for second time the Query result should as follows;
3
3
4
4
Likewise
Pls help me out.
Thanx In Advance,
SIMBHU..

Answer 1

You can use dense_rank setting up a consecutive rank over the values in your table. Restrict the queries to the derived rank. Of course, you´ll have to store the values of the ranks you fetched at least and set the where-clause for each fetch. Thats where Tom´s example comes into play.
The query could look like this:
SQL> select *
  2  from test_
  3  ;
      COL1
         1
         1
         1
         2
         2
         3
         4
         4
         4
         5
         5
      COL1
         5
         5
         6
         6
         7
16 rows selected.
SQL> select col1
  2  from
  3         (
  4         select col1, dense_rank() over (order by col1 asc) n
  5         from test_
  6         order by col1
  7         )
  8  where  n between 1 and 2
  9  ;
      COL1
         1
         1
         1
         2
         2
SQL> select col1
  2  from
  3         (
  4         select col1, dense_rank() over (order by col1 asc) n
  5         from test_
  6         order by col1
  7         )
  8  where n between 3 and 4
  9  ;
      COL1
         3
         4
         4
         4
SQL> Regards,
Gerd