Loop through records in a table and update

Question

Hi there,
Need some help here please. Sorry new to Oracle. I'm working with Oracle 10g.
I have a table like this;
ID Amount Date
123 5000 Oct-07-2011
123 null Oct-09-2011
124 7000 Oct-14-2011
124 null Oct-17-2011
124 null Oct-24-2011
What I'm trying to do here is loop thruogh the records and update the amount that's null with the previous amount with the same ID.
Some sample code that I follow for this?
Thanks very much for your help.

Answer 1

maybe some of this example migth help.
SQL> select id, amount, tdate
  2    from (select 123 id, 5000 amount, to_date('Oct-07-2011','mon-dd-rrrr') tdate from dual union all
  3          select 123 id, null amount, to_date('Oct-09-2011','mon-dd-rrrr') tdate from dual union all
  4          select 124 id, 7000 amount, to_date('Oct-14-2011','mon-dd-rrrr') tdate from dual union all
  5          select 124 id, null amount, to_date('Oct-17-2011','mon-dd-rrrr') tdate from dual union all
  6          select 124 id, null amount, to_date('Oct-24-2011','mon-dd-rrrr') tdate from dual union all
  7          select 124 id, 8000 amount, to_date('Oct-25-2011','mon-dd-rrrr') tdate from dual union all
  8          select 124 id, null amount, to_date('Oct-28-2011','mon-dd-rrrr') tdate from dual)
  9  order by id, tdate;
        ID     AMOUNT TDATE
       123       5000 07-Oct-11
       123            09-Oct-11
       124       7000 14-Oct-11
       124            17-Oct-11
       124            24-Oct-11
       124       8000 25-Oct-11
       124            28-Oct-11
7 rows selected
SQL>
SQL> select id,
  2         last_value(amount ignore nulls) over (partition by id order by tdate) amount,
  3         tdate
  4    from (select 123 id, 5000 amount, to_date('Oct-07-2011','mon-dd-rrrr') tdate from dual union all
  5          select 123 id, null amount, to_date('Oct-09-2011','mon-dd-rrrr') tdate from dual union all
  6          select 124 id, 7000 amount, to_date('Oct-14-2011','mon-dd-rrrr') tdate from dual union all
  7          select 124 id, null amount, to_date('Oct-17-2011','mon-dd-rrrr') tdate from dual union all
  8          select 124 id, null amount, to_date('Oct-24-2011','mon-dd-rrrr') tdate from dual union all
  9          select 124 id, 8000 amount, to_date('Oct-25-2011','mon-dd-rrrr') tdate from dual union all
10          select 124 id, null amount, to_date('Oct-28-2011','mon-dd-rrrr') tdate from dual)
11  order by id, tdate;
        ID     AMOUNT TDATE
       123       5000 07-Oct-11
       123       5000 09-Oct-11
       124       7000 14-Oct-11
       124       7000 17-Oct-11
       124       7000 24-Oct-11
       124       8000 25-Oct-11
       124       8000 28-Oct-11
7 rows selected
SQL>