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.

>>3
That sounds like the most logical thing to do. Is there any point at all in updating first, then checking whether the query executed successfully and only then update the class?