DML(Update) in a report

Question

I have a report, with a query that includes a ROWNUM,
How can I do UPDATE of the table of the query with the printed rownum?
For example, query report is:
SELECT rownum, a.* from mytable a order by ......;
I have to UPDATE one of column, say x of my mytable.
UPDATE mytable Set x = rownum WHERE id_mytable = y;
where (y is column of table mytable printed too)
Thanks in advance for any help

Answer 1

I forgot
I could implement something like
-- start report
--check report progress
LOOP
l_report_status:= report_object_status(l_job_id);
exit when (l_report_status not in('ENQUEUED', 'OPENING_REPORT', 'RUNNING'));
END LOOP;
-- report ended (with/without errors)
IF (l_report_status='FINISHED')
THEN
-- Report run was successful: update database
ELSE
-- Report generation errors
END IF;
but how can i get back rownum printed?
and If it were possible, I would not like to create a TEMP table.
Thanks again