Открытое и доступное подключение Connection. Подключение закрыто

 using System; 

using System.Collections.Generic; 

using System.Linq; 

using System.Text; 

using System.Threading.Tasks; 

using System.Windows; 

using System.Windows.Controls; 

using System.Windows.Data; 

using System.Windows.Documents; 

using System.Windows.Input; 

using System.Windows.Media; 

using System.Windows.Media.Imaging; 

using System.Windows.Shapes; 

using System.Data.SqlClient; 

using System.Data.Entity; 

using System.Data; 

 

namespace WpfApp1 

{ 

    enum RoWState 

    { 

        Existed, 

        New, 

        Modified, 

        ModifiedNew, 

        Deleted 

    } 

 

 

    public partial class Window7admin : Window 

    { 

 

        db database = new db(); 

 

        int selectedRow; 

 

 

        public Window7admin() 

        { 

            InitializeComponent(); 

            CreateColumns(); 

            RefreshDataGridid(dataGridView1); 

 

        } 

 

        private void CreateColumns() 

        { 

             

            DataGridTextColumn textColumn1 = new DataGridTextColumn(); 

            textColumn1.Header = "ID"; 

            textColumn1.Binding = new Binding("ID"); 

            dataGridView1.Columns.Add(textColumn1); 

 

            DataGridTextColumn textColumn2 = new DataGridTextColumn(); 

            textColumn2.Header = "type_of"; 

            textColumn2.Binding = new Binding("Тип товара"); 

            dataGridView1.Columns.Add(textColumn2); 

 

            DataGridTextColumn textColumn3 = new DataGridTextColumn(); 

            textColumn3.Header = "count_of"; 

            textColumn3.Binding = new Binding("Количество"); 

            dataGridView1.Columns.Add(textColumn3); 

 

            DataGridTextColumn textColumn4 = new DataGridTextColumn(); 

            textColumn4.Header = "postavka"; 

            textColumn4.Binding = new Binding("поставщик"); 

            dataGridView1.Columns.Add(textColumn4); 

 

            DataGridTextColumn textColumn5 = new DataGridTextColumn(); 

            textColumn5.Header = "price"; 

            textColumn5.Binding = new Binding("Цена"); 

            dataGridView1.Columns.Add(textColumn5); 

 

            DataGridTextColumn textColumn6 = new DataGridTextColumn(); 

            textColumn6.Header = "IsNew"; 

            textColumn6.Binding = new Binding(String.Empty); 

            dataGridView1.Columns.Add(textColumn6); 

 

        } 

 

 

        private void ReadSingleRow(DataGrid dgw, IDataRecord record) 

        { 

            dgw.Items.Add(record.GetInt32(0)); 

            dgw.Items.Add(record.GetString(1)); 

            dgw.Items.Add(record.GetInt32(2)); 

            dgw.Items.Add(record.GetString(3)); 

            dgw.Items.Add(record.GetInt32(4)); 

            dgw.Items.Add(RoWState.ModifiedNew); 

 

        } 

 

 

        private void RefreshDataGridid(DataGrid dgw) 

        { 

            dgw.Items.Clear(); 

 

            string queryString = $"select * from price"; 

 

            SqlCommand command = new SqlCommand(queryString, database.getConnection()); 

 

            database.getConnection(); 

 

// Вот тут ошибка SqlDataReader reader = command.ExecuteReader(); 



            while(reader.Read()) 

            { 

                ReadSingleRow(dgw, reader); 

            } 

            reader.Close(); 

        }