Database programming

G'day /prog/

I'm writing a java application with a mysql db backend (indeed, performance is not what I'm after), but I'm struggling a bit. How does one go about saving data? Do you execute an update query whenever a class representing a table is changed, or would there be an interval? Or am I going about this entirely wrong?
Your advice will be greatly appreciated.

>>14
Enjoy wasting three hours collecting various libraries and dependencies for Hibernate. Oh, and enjoy spending a few more hours on setting up the config file. You could've probably solved any problem in that time using java.sql and friends.