private void LoginButton_Click(object sender, RoutedEventArgs e)
    {
        try
        {
            SqlConnection conn = new SqlConnection("Data Source=DB;Initial Catalog=projectDB;User ID=username;Password=password");
            SqlDataAdapter sqa = new SqlDataAdapter("SELECT COUNT(*) FROM user WHERE userName = '" + UsernameTextBox.Text + "' AND password = '" + PasswordTextBox.Password + "'", conn);
            DataTable dt = new DataTable();
            sqa.Fill(dt);

            if (dt.Rows[0][0].ToString() == "1")
            {
                this.Hide();
            }
            else
            {
                MessageBox.Show("Username/Password is incorrect. Please try again");
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }
}