hi, I'm c# developer, I'll create the application using Xamarin, so you will have android and ios versions of the app.
about the database... an api is needed, I can create it, that's not a problem, but if you are thinking on access the database directly from the app, I have to say this: that is not a good or recommended approach, that will lead to connectivity problems and also the different platforms does not have drivers for the different database providers.
if you Alfre interested, contact me