我无法在Visual Studio的列中看到变量的附加值，但我在SQL服务器中看到它们。为什么？

Question

我正在创建一个Visual Studio项目，用于从MS SQL服务器添加和读取客户。我无法看到通过Visual Studio获得的值。

这是SQL代码：

create Table Person
(

Id int PRIMARY KEY,
FirstName varchar (15),
LastName varchar (15),
TaxNbr int,
BirthDate DATETIME,
AktivStatus varchar (15),
);

这是C＃的一部分，我在为客户添加新值：

private void Button_AddCustomer(object sender, RoutedEventArgs e)
    {


        Person customer = new Person();
        int number;
        customer.FirstName = FirstName.Text.Trim();
        customer.LastName = LastName.Text.Trim();
        if (int.TryParse(TaxNbr.Text, out number) == false) MessageBox.Show("Must add a valid tax number");
        if (number < 0 || number > 999) MessageBox.Show("Invalid Tax Number. Must be between 0 and 999");
        else customer.TaxNbr = number;

        customer.BirthDate = BirthDate.DisplayDate; 
        if (Aktiven.IsChecked == true) customer.AktivStatus = "Aktiven";
        if (Neaktiven.IsChecked == true)
        {
            customer.AktivStatus = "Neaktiven";
        }

        CustomerClass.AddCustomer(customer);
        DialogResult = true;

    }

我已将其与SQL类连接：

public static class CustomerClass
{
    #region

    public static void AddCustomer(Person customer)
    {
        using (CustomerDataContext conn = new CustomerDataContext())
        {
            conn.Persons.InsertOnSubmit(customer);
            conn.SubmitChanges();

        }

    }
    #endregion
}

请帮忙，我是初学者:)