Dear Mr. Ram KM,
1. It is possible to communicate the stand-alone pdf to the database via webservices.
2. webservices are best used for offline forms having submit button functionality.
3. we can call webservices(WSDL) by using javaScript calls.
3. It is also possible to communicate with the database by using data source. But I wouldn't recommend you to use this, because each client machine should contain DSN source.
4. It is not known that stand-alone pdf communicate with the database by using JDBC calls via thin driver.
I am guessing a stand-alone pdf shouldn't contain JVM. As we all know that this methodology is possible at the server side.
The above solution is given to the best of my knowledge.
Regards,
Ramesh Punugubati
Adobe Developer
Tcs,India.