Problem with android app (remote server ,no Internet access)

Can someone give me an idea or point me in the right direction about following matter:

I need to make android app that will do some things with remote oracle database (take some data, insert some data, ...).

I can do that, but the trick is, app owner needs to be able to do that offline (because he doesn't have internet everywhere), then when user connects to internet, somehow transfer those offline changes in local android database to oracle database. I never did something like that.Any pointers?

Should I somehow copy remote oracle database to local android SQLite database?So user can work offline, and then when he connect to internet somehow detect changes he made and transfer them to remote database?

More info about app: About 15-20 users will work with this app.They are traveling salesmen.Making multiple orders with app(offline) then when they have internet access, somehow trasfer all those orders(records in multiple tables) to remote database.

A can do this easy if they would have internet access the whole time.Make php webservice on remote server, returning JSON data to app, then when they make new records on app,app calls php webservice then submit that new recordthem to database.But the problem is that they want to work offline the whole day, then at the end of the day just submit their work to remote database.

Sorry for long text, and thanks for any help.