private void pokazpola()
        {
            EmployeeDbcontext db = new EmployeeDbcontext();

            switch (RadioButtonList1.SelectedValue)
            {
            case "Permament":
            {
                GridView1.DataSource = db.Employees.OfType <PermanentEmployee>().ToList();
                GridView1.DataBind();
                break;
            }

            case "Contract":
            {
                GridView1.DataSource = db.Employees.OfType <ContractEmployee>().ToList();
                GridView1.DataBind();
                break;
            }

            default:
            {
                GridView1.DataSource = Dane(db.Employees.ToList());
                GridView1.DataBind();
                break;
            }
            }
        }
        protected void Button2_Click(object sender, EventArgs e)
        {
            EmployeeDbcontext db = new EmployeeDbcontext();
            PermanentEmployee pe = new PermanentEmployee()
            {
                FirstName    = "Mike",
                LastName     = "Brown",
                Gender       = "Male",
                AnnualSalary = 70000,
            };

            db.Employees.Add(pe);
            db.SaveChanges();
            pokazpola();
        }
        protected void Button1_Click(object sender, EventArgs e)
        {
            EmployeeDbcontext db = new EmployeeDbcontext();
            ContractEmployee  ce = new ContractEmployee()
            {
                FirstName   = "Stacy",
                LastName    = "Josh",
                Gender      = "Female",
                HourlyPay   = 50,
                HoursWorked = 120
            };

            db.Employees.Add(ce);
            db.SaveChanges();
            pokazpola();
        }