Привязка treeview к базе данных

I need to load the  following table in the form of a treeview in my C# WPF Application. This is my table : Drinks
DrinksId     DrinksName   Level1  Level2   Level3   Level4   Level5
  1           Drinks         0      0        0        0         0
  2           Cold           1      0        0        0         0
  3           Pepsi          1      1        0        0         0
  4           Light          1      1        1        0         0
  5           Zero           1      1        2        0         0
  6           Heavy          1      1        3        0         0
  7           Cola           1      2        0        0         0
  8           Zero           1      2        1        0         0
  9           Light          1      2        2        0         0
  10          One-Light      1      2        2        1         0
  11          Two-Light      1      2        2        2         0
  12          7-UP           1      3        0        0         0
  13          Hot            2      0        0        0         0
  14          Coffee         2      1        0        0         0
  15          Black          2      1        1        0         0
  16          Espresso       2      1        2        0         0
  
 My treeview should be like this:-
      Drinks
      |----Cold
      |--------Pepsi
      |------------Light
      |------------Zero
      |------------Heavy
      |--------Cola
      |------------Zero
      |------------Light
      |----------------One-Light
      |----------------Two-Light
      |--------7-Up
      |------Hot
      |---------Coffee
      |--------------Black
      |--------------Espresso
      
I tried with Hierarchical data template to display the levels  in my XAML. I tried binding my treeview to the Observable Collection, as I need to add, remove, update items later. 
Now nothing is getting displayed. I don't know where I am going wrong. Please Help

<pre><Window.Resources>
        <DataTemplate x:Key="level5">
            <TextBlock Text="{Binding DrinkName}"/>
        </DataTemplate>
        <HierarchicalDataTemplate x:Key="level4" ItemTemplate="{StaticResource level5}">
            <TextBlock Text="{Binding DrinkName}"/>
        </HierarchicalDataTemplate>
        <HierarchicalDataTemplate x:Key="level3" ItemTemplate="{StaticResource level4}">
            <TextBlock Text="{Binding DrinkName}"/>
        </HierarchicalDataTemplate>
        <HierarchicalDataTemplate x:Key="level2" ItemTemplate="{StaticResource level3}">
            <TextBlock Text="{Binding DrinkName}"/>
        </HierarchicalDataTemplate>
        <HierarchicalDataTemplate x:Key="level1"  ItemTemplate="{StaticResource level2}">
            <TextBlock Text="{Binding DrinkName}"/>
        </HierarchicalDataTemplate>
    </Window.Resources>
    <Grid>
        <TreeView Name="treeviewdrinks" ItemsSource="{Binding Mytv,UpdateSourceTrigger=PropertyChanged}" />
    </Grid>

<pre>public MainWindow()
        {
            InitializeComponent();
            LoadTreeView();
        }
        private void LoadTreeView()
        {
                string connectionString = @"Provider=SQLOLEDB.1; Data Source=PBA-PC\SQLEXPRESS; Initial Catalog = DemoDB; Integrated Security=SSPI;";
                OleDbConnection oledbconn = new OleDbConnection(connectionString);
                oledbconn.Open();
                OleDbDataAdapter oleda = new OleDbDataAdapter();
                Mytv = new ObservableCollection<treeviewcollection>();
                treeviewdrinks.DataContext = Mytv;
                try
                {

                    OleDbCommand olecmd = new OleDbCommand("Select * from Drinks Where Level1 <> 0 and Level2 = 0 and Level3 = 0 and Level4 = 0 and Level5 = 0", oledbconn);
                    DataSet ds = new DataSet();
                    //ds.Relations.Add()
                    oleda.SelectCommand = olecmd;
                    oleda.Fill(ds);
                    foreach (DataRow dr in ds.Tables[0].Rows)
                    {
                        Mytv.Add(new treeviewcollection { DrinkName = dr["DrinkName"].ToString() });
                        var step1 = "";
                        OleDbCommand olecmd1 = new OleDbCommand("SELECT * From Drinks Where Level1 = ? and Level2 <> 0 and Level3 = 0 and Level4 = 0 and Level5 = 0", oledbconn);
                        // MessageBox.Show(dr["Level1"].ToString());
                        olecmd1.Parameters.AddWithValue(@step1, dr["Level1"].ToString());
                        OleDbDataAdapter oleda1 = new OleDbDataAdapter(olecmd1);
                        DataSet ds1 = new DataSet();
                        oleda1.Fill(ds1);
                        foreach (DataRow dr1 in ds1.Tables[0].Rows)
                        {
                            Mytv.Add(new treeviewcollection { DrinkName = dr1["DrinkName"].ToString() });
                            var step2 = "";
                            OleDbCommand olecmd2 = new OleDbCommand("SELECT * From Drinks Where Level1 = ? and Level2 = ? and Level3 <> 0 and Level4 = 0 and Level5 = 0", oledbconn);
                            olecmd2.Parameters.AddWithValue(@step1, dr["Level1"].ToString());
                            olecmd2.Parameters.AddWithValue(@step2, dr1["Level2"].ToString());
                            OleDbDataAdapter oleda2 = new OleDbDataAdapter(olecmd2);
                            DataSet ds2 = new DataSet();
                            oleda2.Fill(ds2);
                            foreach (DataRow dr2 in ds2.Tables[0].Rows)
                            {
                                Mytv.Add(new treeviewcollection { DrinkName = dr2["DrinkName"].ToString() });
                                var step3 = "";
                                OleDbCommand olecmd3 = new OleDbCommand("SELECT * From Drinks Where Level1 = ? and Level2 = ? and Level3 = ? and Level4  <> 0 and Level5 = 0", oledbconn);
                                olecmd3.Parameters.AddWithValue(@step1, dr["Level1"].ToString());
                                olecmd3.Parameters.AddWithValue(@step2, dr1["Level2"].ToString());
                                olecmd3.Parameters.AddWithValue(@step3, dr2["Level3"].ToString());
                                OleDbDataAdapter oleda3 = new OleDbDataAdapter(olecmd3);
                                DataSet ds3 = new DataSet();
                                oleda3.Fill(ds3);
                                foreach (DataRow dr3 in ds3.Tables[0].Rows)
                                {
                                    Mytv.Add(new treeviewcollection { DrinkName = dr3["DrinkName"].ToString() });
                                    var step4 = "";
                                    OleDbCommand olecmd4 = new OleDbCommand("SELECT  * From Drinks Where Level1 = ? and Level2 = ? and Level3 = ? and Level4 = ? and Level5  <> 0", oledbconn);
                                    olecmd4.Parameters.AddWithValue(@step1, dr["Level1"].ToString());
                                    olecmd4.Parameters.AddWithValue(@step2, dr1["Level2"].ToString());
                                    olecmd4.Parameters.AddWithValue(@step3, dr2["Level3"].ToString());
                                    olecmd4.Parameters.AddWithValue(@step4, dr3["Level4"].ToString());
                                    OleDbDataAdapter oleda4 = new OleDbDataAdapter(olecmd4);
                                    DataSet ds4 = new DataSet();
                                    oleda4.Fill(ds4);
                                    foreach (DataRow dr4 in ds4.Tables[0].Rows)
                                    {
                                        Mytv.Add(new treeviewcollection { DrinkName = dr4["DrinkName"].ToString() });

                                    }
                                }
                            }
                        }
                    }

                } // End try

                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
                finally
                {

                    oledbconn.Close();
                }
        }
        private ObservableCollection<treeviewcollection> _mytv;
        public ObservableCollection<treeviewcollection> Mytv
        {
            get { return _mytv; }
            set
            {
                _mytv = value;
                OnPropertyChanged("Mytv");
            }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        private void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
        public class treeviewcollection
        {

            public string DrinkName { get; set; }


        }
          public class level5 
           {

               public string DrinkName { get; set; }


           }
           public class level4
           { 
               public string DrinkName { get; set; }
               ObservableCollection<level5> l4;
           }
           public class level3
           {

               public string DrinkName { get; set; }
               ObservableCollection<level4> l3;

           }
           public class level2 
           {
              public string DrinkName { get; set; }
              ObservableCollection<level3> l2;
           }
           public class level1
           { 
               public string DrinkName { get; set; }
               ObservableCollection<level2> l1;
           }


    }