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.

>>4

instead of querying for success, have some algorithm check the data locally. quering before submit can be used for unique data