Write your database update as a regular script (which, of course can call other
java programs to actually to do the update or use something like isql) and then all you use cron for is to schedule the execution of that script. Once you have your script written, it is a simple step to add it to cron. Take a look at the man pages for cron or ask your sysadmin.
[ January 10, 2006: Message edited by: Don Morgan ]