Java safe communication with database from multiple sessions

I have to develop a small application for my company in Java which should show data from a database. The shown data should be editable in the gui and with a save button the edited data should be written to the database. My question is now how to handle the database communication because multiple users will use the application at the same time? I think there will be a problem if person A is watching the data and person B does a change. If now person A saves his change the data from person B is lost.

I couldn t find anything in the internet because i dont know which keyword i have to use for the search. I only could find something called dao pattern but i dont think thats the thing im looking for.

Hope you can help me.