I've created a Sql plugin for Xamarin on top of the Sqlite-net plugin.
With this plugin you can add a sql database to your apps with a single line of code.
This is the nuget package: https://www.nuget.org/packages/MarcTron.Sqlite/
and you can find a tutorial here: http://www.xamarinexpert.it/2018/03/01/sqlite-made-easy/
If you have any questions or problems ask me.