What happen with my data if I uninstall my application?

It will depend on your device's platform.

Android/iOS Platform
Your database and binaries are stored in the same private location, it means that if you uninstall the application, it will remove all files in this location including your database.

Linux/Windows Platform
Your database is stored in a separate location from the binaries. Therefore, your database won't be deleted after unintalling the application.