SQL & PL/SQL

Hi,
I have 200 jobs and want to modify the next execution date to 24 of january (conserving the same hour ). How can I use the following to change all jobs in user_jobs table :
[code ]
•If the parameters what, next_date, or interval are NULL, then leave that value as it is.

Example

BEGIN
DBMS_JOB.CHANGE(14144, null, null, 'sysdate+3');
COMMIT;
END;



Thank you