Upgrading DB in Android

I am aware of how the upgrade method works, I am confused at certain points:

1) At the start my DB version was 1 my app version was 1.

2) Now I upgraded my DB version to 2 and my app version is 2.

3) I want to upgrade DB to 3 and app to 3.

Question: What happens to people who are upgrading from app version 1 to app version 3? Will they get the upgrade of DB to 2 and then to 3? Or do I need to write code for that? How do I maintain such flags?