what is the method need to use in combobox to get all related data based on first letter enter

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
AutoCompleteStringCollection l1 = new AutoCompleteStringCollection();
OleDbDataAdapter da = new OleDbDataAdapter("SELECT Name FROM name table ", Con1);
                DataSet ds = new DataSet();
                Con1.Open(); ;
                da.Fill(ds);
               
                for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
                    l1.Add(ds.Tables[0].Rows[i].ItemArray[0].ToString());

                textBox1.AutoCompleteCustomSource = l1;
           }