Query for a simple caching mechanism

Question

Suppose that I have a CONTRACT table with 50000 records.
I want to get the last inserted 100 records and then the next 100 and so on...
In other words, like using a file pointer I want to get the next n records and then the next n records... Because I cannot load all the records in memory.
I wrote a query with an IN clause and ROWNUM pseudo-column for the issue. But it doesn't result like i expected. Here is what it looks like:
SELECT contract.contract_id
FROM vw_contract contract
WHERE ROWNUM <= 2
AND contract.contract_date BETWEEN TO_DATE('03.01.2005','DD.MM.YYYY') AND TO_DATE('04.02.2005','DD.MM.YYYY')
AND contract.contract_id NOT IN (SELECT k.contract_id
FROM vv_yk_dp_contract c
WHERE ROWNUM <= 2
AND c.contract_date BETWEEN TO_DATE('03.01.2005','DD.MM.YYYY') AND TO_DATE('04.02.2005','DD.MM.YYYY'));
To test it, I select the first 4 records. That query should give me the third and forth records but it doesn't. Also, the query is slow.
Should I use a cursor? But, with PL/SQL how can a cursor be used for getting records between Nth and Mth?
What kind of strategy should be used for such a simple caching issue?

Answer 1

I want to get the last inserted 100 records and then the next 100 and so on...
In other words, like using a file pointer I want to get the next n records and then >>the next n records...Something like this ? (But the solution depends on what kind of client you use).
SQL> create or replace type t_varchar is table of varchar2(10)
  2  /
Type created.
SQL> create or replace package pkg1
  2  is
  3   cursor a is select ename from emp order by 1;
  4  end;
  5  /
Package created.
SQL> create or replace function get_rows
  2  return t_varchar
  3  pipelined
  4  is
  5   name emp.ename%type;
  6  begin
  7   if not pkg1.a%isopen then
  8    open pkg1.a;
  9   end if;
10   loop
11     fetch pkg1.a into name;
12     exit when pkg1.a%notfound;
13     pipe row(name);
14   end loop;
15   close pkg1.a;
16   return;
17  end;
18  /
Function created.
SQL> select /* from 1 to 3th */ * from table(get_rows) where rownum <=3;
COLUMN_VAL
ADAMS
ALLEN
BLAKE
SQL> select /* from 4th to 9th */ * from table(get_rows) where rownum <= 6;
COLUMN_VAL
CLARK
FORD
JAMES
JONES
KING
MARTIN
6 rows selected.
SQL> select /* from 10th to 14th */ * from table(get_rows) where rownum <= 5;
COLUMN_VAL
MILLER
SCOTT
SMITH
TURNER
WARDRgds.