C# .NET (WINDOWS FORM) Login System.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace Grou
{
    public partial class Frm_Login : Form
    {

        MySqlConnection conn = new MySqlConnection(Properties.Settings.Default.conexao);
        private Boolean usertype;
        public Frm_Login()
        {
            InitializeComponent();
        }

        private void Login()
        {
            if (!String.IsNullOrEmpty(TxtLogin.Text) || !String.IsNullOrEmpty(TxtSenha.Text))
            {
                conn.Open();
                try
                {
                    MySqlCommand cmd = new MySqlCommand("SELECT username,password,nivel FROM grou_login WHERE username = @user AND password = @pass", conn);
                    cmd.Parameters.AddWithValue("@user", TxtLogin.Text); //parametros para usuario;
                    cmd.Parameters.AddWithValue("@pass", TxtSenha.Text); //parametros para senha
                    MySqlDataReader mdr = cmd.ExecuteReader();  //Data Reader (Adaptador para obj cmd)
                    if (mdr.Read() == true)
                    {
                        usertype = Convert.ToBoolean(mdr["nivel"]);
                        if (usertype == true)
                        {
                            MessageBox.Show("ADMIN LOGADO!");
                        }
                        else
                        {
                            MessageBox.Show("NORMAL USER LOGADO");
                        }

                    }
                    else
                    {
                        MessageBox.Show("Nome de usuário ou senha inválidos, Por favor tente mais tarde.");
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Ops! houve um erro desconhecido~~:", Convert.ToString(ex));
                }
                finally
                {
                    conn.Close();
                }
            }
            else
            {
                MessageBox.Show("Ops! Preencha os campos corretamente!"); //se campo for vazio
            }

        }

        private void BtnLogin_Click(object sender, EventArgs e) //Btn_LOGIN
        {
            Login();
        }

        private void BtnCancel_Click(object sender, EventArgs e) //Btn_CANCEL
        {
            Application.ExitThread();
        }

        private void TxtLogin_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == 13)
            {
                Login();
            }
        }

        private void TxtSenha_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (e.KeyChar == 13)
            {
                Login();
            }
        }
    }
}