private void boxForTableList_SelectedIndexChanged(object sender, EventArgs e)
 {
     lstDataView.Items.Clear();
     if (boxForTableList.SelectedIndex == 1)
     {
         using (var context = new Sales.EntityServices.AppContext())
         {
             foreach (var record in context.Customers.ToList())
             {
                 lstDataView.Items.Add($"{record.Name}  :  {record.FamilyName}");
             }
         }
     }
     else if (boxForTableList.SelectedIndex == 2)
     {
         using (var context = new Sales.EntityServices.AppContext())
         {
             foreach (var record in context.Sellers.ToList())
             {
                 lstDataView.Items.Add($"{record.Name}  :  {record.FamilyName}");
             }
         }
     }
     else if (boxForTableList.SelectedIndex == 3)
     {
         using (var context = new Sales.EntityServices.AppContext())
         {
             foreach (var record in context.Sales.ToList())
             {
                 lstDataView.Items.Add($"{record.Customer.Name} {record.Customer.FamilyName}  :  {record.Seller.Name} {record.Seller.FamilyName}");
             }
         }
     }
 }
        public MainForm()
        {
            InitializeComponent();

            using (var context = new Sales.EntityServices.AppContext())
            {
                tableNames =
                    context.Database.SqlQuery <string>("SELECT name FROM sys.tables where name!='__MigrationHistory' ORDER BY name").ToList();
            }
            foreach (var name in tableNames)
            {
                boxForTableList.Items.Add(name);
            }
        }