如何使用函数从sqlite数据库中获取数据

我正在制作Xamarin表单中的应用程序，但无论我尝试什么，我都无法获得sqlite数据库的工作。我想选择所有类别，其中menu_ID = 1我怎么能做到这一点?我需要这个代码在另一个页面(categoripage . example .cs)可以帮助我这个?

下面是我使用的一些代码:

(Tables.cs):

namespace AmsterdamTheMapV3
{
    public class Categories
    {
        [PrimaryKey, AutoIncrement]
        public int ID { get; set; }
        public int Menu_ID { get; set; }
        public string Name { get; set; }
        public Categories()
        {
        }
    }
    public class Places
    {
        [PrimaryKey, AutoIncrement]
        public int ID { get; set; }
        public int Categorie_ID { get; set; }
        public string Name { get; set; }
        public Boolean Featured { get; set; }
        public string OpenHours { get; set; }
        public string Info { get; set; }
        public string Images { get; set; }
        public string Phone { get; set; }
        public string Website { get; set; }
        public string Adress { get; set; }
        public Places()
        {
        }
    }
    public class Events
    {
        [PrimaryKey, AutoIncrement]
        public int ID { get; set; }
        public Events()
        {
        }
    }
}

数据库助手(TheMapDB.cs):

public class TheMapDB
{
    private SQLiteConnection db;
    public TheMapDB()
    {
        //Getting conection and Creating table  
        db = DependencyService.Get<ISQLite>().GetConnection();
        db.CreateTable<Categories>();
        db.CreateTable<Places>();
        db.CreateTable<Events>();
        var categories = new Categories()
        {
            ID = 1,
            Menu_ID = 1,
            Name = "test"
        };
        db.Insert(categories);   // Insert the object in the database
    }

    public IEnumerable<Categories> GetCategories()
    {
        return (from t in db.Table<Categories>() select t).ToList();
    }
    //Get specific Categorie
    public Categories GetCategorie(int id)
    {
        return db.Table<Categories>().FirstOrDefault(t => t.ID == id);
    }
    //Delete specific Categorie
    public void DeleteCategorie(int id)
    {
        db.Delete<Categories>(id);
    }
    //Add new student to Categorie
    public void AddCategorie(Categories categorie)
    {
        db.Insert(categorie);
    }
}
}

CategoriePage.xaml.cs:

 public partial class CategoriePage : ContentPage
    {
        static TheMapDB database;
        TheMapDB categorie = new TheMapDB();
        public CategoriePage(String txt)
        {
            InitializeComponent();
            var layout = new StackLayout { Padding = new Thickness(5, 10) };
            this.Content = layout;
            if(txt.Equals("1"))
            {
                txt = "this text is number 1";
                //needed code can't find soluction
            }
            var label = new Label { Text = txt, TextColor = Color.FromHex("#77d065"), FontSize = 20 };
            layout.Children.Add(label);
        }
    }

提前谢谢你

public List<Category> GetCategoryByID(int menuID)
{
    return db.Table<Category>().Where(x => x.menu_ID == menuID).ToList();
}