Need to fetch the last record/row from a table

Question

Hi,
I have a requirement like fetching the closing balance of the last record of the table and inserting the same into the opening balance of the immediatetly created next record.
In simple words, I need to fetch a value from the last row of the record.
For example, I use the below query,
select rownum, empno, ename from emp
where rownum = (select count(rownum) from emp);
But, the above query does not return any of the record.
Hence, need help on this.
Regards,
Shivakumar A
Edited by: shiva on Mar 27, 2011 10:14 PM

Answer 1

Rows in a table are inherently unordered. In order to introduce the concept of "first" and "last", you would need to specify how to order the rows which would require that there was one or more columns in the table that you could order by in order to determine the "last" record.
In your closing balance example, if we assume that there is something like a BALANCE_DATE column,
SELECT account_number, balance_amount, balance_date
  FROM (
    SELECT account_number,
           balance_amount,
           balance_date,
           rank() over (partition by account_number order by balance_date desc) rnk
      FROM table_of_balances )
WHERE rnk = 1Justin