SQL & PL/SQL

Hi all ,

please suggest me ,your help is greatly appreciated .

I have to update a job to run everyday at 8:00 pm .please verify if this is okay or do  i  need to make any more changes here .

DECLARE
   njob_id   all_jobs.job%TYPE;
BEGIN
   SELECT job
     INTO njob_id
     FROM all_jobs
   WHERE UPPER (what) LIKE '%EMP%';

   DBMS_JOB.INTERVAL(njob_id, 'NEXT_DAY(TRUNC(SYSDATE+1 ) + 20/24');
   DBMS_JOB.NEXT_DATE(njob_id, (TRUNC(SYSDATE+1 )+20/24);
   DBMS_OUTPUT.put_line ('The job interval is successfully changed');
EXCEPTION
   WHEN OTHERS
   THEN
      DBMS_OUTPUT.put_line (   'ERROR in changing the job interval !'
                            || SUBSTR (SQLERRM, 1, 200)
                           );
END;