Подключение к БД SQLite

using System;
using Xamarin.Forms;
using System.IO;
using System.Data;
using System.Data.Common;
 
using Microsoft.Data.Sqlite;   // <<< Первая библиотека 
 
namespace App1
{
    public partial class View1 : ContentPage
    {
       public View1()
        {
            InitializeComponent();
        }
        void picker1_SelectedIndexChanged(object sender, EventArgs e)
        {        
         string selection = picker1.Items[picker1.SelectedIndex];
            using (SqliteConnection connection = new SqliteConnection(@"Data Source =  " + Environment.CurrentDirectory + "localBD.db"))
            {
                connection.Open();
                using (SqliteCommand command = new SqliteCommand())
                {
                    command.CommandText = "SELECT Model From Cars WHERE  Mark = " + selection + connection;
                    command.CommandType = CommandType.Text;
                    command.ExecuteNonQuery();
                    SqliteDataReader reader = command.ExecuteReader();
                    while (reader.Read())
                    {
                        picker2.Items.Add(Convert.ToString(reader["Model"]));
                    }
                }
            }
        }
    }
}

 using (SqliteConnection connection = new SqliteConnection(@"Data Source =  " + Environment.CurrentDirectory + "localBD.db"))

using System;
using Xamarin.Forms;
using System.IO;
using System.Data;
using System.Data.Common;
 
 
 
//using Microsoft.Data.Sqlite;
using System.Data.SQLite;
 
namespace App1
{
    public partial class View1 : ContentPage
    {       
        public View1()
        {
            InitializeComponent();
        }
        void picker1_SelectedIndexChanged(object sender, EventArgs e)
        {         
        string selection = picker1.Items[picker1.SelectedIndex];
            using (SQLiteConnection connection = new SQLiteConnection(@"Data Source =  " + Environment.CurrentDirectory + "localBD.db"))
            {
                connection.Open();
               using (SQLiteCommand command = new SQLiteCommand(connection))
                {
                    command.CommandText = "SELECT Model From Cars WHERE  Mark = " + selection + connection;
                    command.CommandType = CommandType.Text;
                    command.ExecuteNonQuery();
                    SQLiteDataReader reader = command.ExecuteReader();
                    while (reader.Read())
                    {
                        picker2.Items.Add(Convert.ToString(reader["Model"]));
                    }
                }
            }
        }
    }
}

   void picker1_SelectedIndexChanged(object sender, EventArgs e)
        {

using SQLite;
using System;
using System.IO;
using Xamarin.Forms;
 
namespace App5
{
 
    public partial class MainPage : ContentPage
    {
 
        public class Cars
        {
            [PrimaryKey, AutoIncrement]
            public int Id { get; set; }
 
            public string Mark { get; set; }
 
            public string Model { get; set; }
        }
        private readonly SQLiteConnection db;
 
        public MainPage()
        {
            string dbPath = Path.Combine(
           Environment.GetFolderPath(Environment.SpecialFolder.Personal),
           "localDB.db");
 
            InitializeComponent();
            db = new SQLiteConnection(dbPath);
            db.CreateTable<Cars> ();
        }
 
        void picker1_SelectedIndexChanged(object sender, EventArgs e)
        {
 
 
 
            string selection = picker1.Items[picker1.SelectedIndex];
 
              
            var cars = db.Query<Cars>("SELECT Model From Cars WHERE [Mark] = ?", selection);
            picker2.ItemsSource = cars;
            int count = db.Table<Cars> ().Count();
 
            for (int i = 0; i  < count; i++)
            {
 
            }
           DisplayAlert("Уведомление", Convert.ToString(count), "ОK");
}
}
}

var cars = db.Query<Cars>("SELECT Model From Cars WHERE [Mark] = ?\"", selection, "\"");