Gist for https://github.com/twolf611/Xamarin.Forms-SQLiteExample

Database.cs

using System;
using System.Collections.Generic;
using System.Linq;
using SQLite;
using Xamarin.Forms;

namespace SQLiteExample {
  public class Database {
    static object locker = new object();
    ISQLiteService SQLite {
      get {
        return DependencyService.Get<ISQLiteService>();
      }
    }
    readonly SQLiteConnection connection;
    readonly string DatabaseName;

    public Database(string databaseName) {
      DatabaseName = databaseName;
      connection = SQLite.GetConnection(DatabaseName);
    }
  
    public void CreateTable<T>() {
      lock (locker) {
        connection.CreateTable<T>();
      }
    }

    public long GetSize() {
      return SQLite.GetSize(DatabaseName);
    }

    public int SaveItem<T>(T item) {
      lock (locker) {
        var id = ((BaseItem)(object)item).ID;
        if (id != 0) {
          connection.Update(item);
          return id;
        }
        else {
          return connection.Insert(item);
        }
      }
    }

    public void ExecuteQuery(string query, object[] args) {
      lock (locker) {
        connection.Execute(query, args);
      }
    }

    public List<T> Query<T>(string query, object[] args) where T : new() {
      lock (locker) {
        return connection.Query<T>(query, args);
      }
    }

    public IEnumerable<T> GetItems<T>() where T : new() {
      lock (locker) {
        return (from i in connection.Table<T>() select i).ToList();
      }
    }

    public int DeleteItem<T>(int id) {
      lock (locker) {
        return connection.Delete<T>(id);
      }
    }

    public int DeleteAll<T>() {
      lock (locker) {
        return connection.DeleteAll<T>();
      }
    }
  }
}