C# authentication by role in SQL DB table

namespace WpfApplication1
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        public MainWindow()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, RoutedEventArgs e)
        {
            SqlConnection con = new SqlConnection("Data Source=(local);Initial Catalog=Aukcija;Integrated Security=True");
            con.Open();
            SqlDataAdapter sda = new SqlDataAdapter("SELECT Role FROM users WHERE Username='"+ textBoxUser.Text +"' and Password='"+ passBoxPwd.Password + "' ", con);
            DataTable dt = new DataTable();
            sda.Fill(dt);
            if (dt.Rows.Count == 1)
            {
                this.Hide();
                Window1 w1 = new Window1();
                w1.Show();
            }
            con.Close();
        }

        private void button2_Click(object sender, RoutedEventArgs e)
        {
            this.Close();
        }
    }
}