SELECT ROWNUM and ORDEY BY DATE

Question

I want to select the most recent row from a table where one column is null and have the following query.
'select * from table_name where rownum < 2 and column1 is null order by date_stamp desc'
Date_stamp column holds the system date when each row was inserted int this table. So whenever a row is insered into this table the date_stamp column always gets the curent sysem date.
This is always returning me the oldest row not the most recent row. I tried to use
GREATEST(select date_stamp from table_name)
but it did not work as GREATEST expects dats seprated by commas.
If there is a function which can convert the date_stamp to a numerical value(milliseconds from 1970 or something like what java has) I can order by that number and the most recent date should have the highest numerical value and thus should work.
Is there a way to do this without having to write a procedure or function? I'm using 8i(8.1.7).
Thanks

Answer 1

Note that ORDER BY and ROWNUM cannot be combined the way you have in your query. Try this:
SELECT *
FROM   (SELECT *
        FROM   table_name
        WHERE  column1 IS NULL
        ORDER  BY date_stamp DESC)
WHERE  rownum = 1