Using SQLite database in Xamarin.Forms

Using Xamarin.Forms (your link is for Android!), you will have to use some kind of abstraction from your shared project in order to access your database (which is platform specific). This is how you can basically get the right storage path per platform.

This means basically to create an Interface in the shared project, i.e:

public interface IFileHelper
{
  string GetLocalFilePath(string filename);
}

Then, you must implement the platform specific parts. I.e Android:

[assembly: Dependency(typeof(FileHelper))]
namespace Todo.Droid
{
    public class FileHelper : IFileHelper
    {
        public string GetLocalFilePath(string filename)
        {
            string path = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
            return Path.Combine(path, filename);
        }
    }
}

iOS:

[assembly: Dependency(typeof(FileHelper))]
namespace Todo.iOS
{
    public class FileHelper : IFileHelper
    {
        public string GetLocalFilePath(string filename)
        {
            string docFolder = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
            string libFolder = Path.Combine(docFolder, "..", "Library", "Databases");

            if (!Directory.Exists(libFolder))
            {
                Directory.CreateDirectory(libFolder);
            }

            return Path.Combine(libFolder, filename);
        }
    }
}

UWP:

using Windows.Storage;
...

[assembly: Dependency(typeof(FileHelper))]
namespace Todo.UWP
{
    public class FileHelper : IFileHelper
    {
        public string GetLocalFilePath(string filename)
        {
            return Path.Combine(ApplicationData.Current.LocalFolder.Path, filename);
        }
    }
}

Then to retrieve and use The most simple approach is to use Xamarin's DependencyService. More info here.

Here is the official documentation about local databases.

Hope it helps!