private void buttonUpdate_Click(object sender, EventArgs e)  //ok
        {
            Employee emp = new Employee();

            emp.EmployeeId = Convert.ToInt32(textBoxEmployeeId.Text);
            emp.FirstName  = textBoxFirstName.Text;
            emp.LastName   = textBoxLastName.Text;
            emp.JobTitle   = textBoxJobTitle.Text;
            emp.UserType   = textBoxUserType.Text;
            emp.Password   = textBoxPassword.Text;
            emp.Email      = textBoxEmail.Text;

            emp.DeleteEmployee(emp.EmployeeId);
            emp.SaveEmployee(emp);

            MessageBox.Show("Employee has been modified.");
        }
        private void buttonAdd_Click(object sender, EventArgs e) //OK
        {
            Employee emp = new Employee();

            emp.FirstName = textBoxFirstName.Text;
            emp.LastName  = textBoxLastName.Text;
            emp.JobTitle  = textBoxJobTitle.Text;
            emp.UserType  = textBoxUserType.Text;
            emp.Password  = textBoxPassword.Text;
            emp.Email     = textBoxEmail.Text;

            if (emp.SaveEmployee(emp))
            {
                MessageBox.Show("Employee saved!");
            }
            else
            {
                MessageBox.Show("Saving problem.");
            }
        }