qwerty/Cafe11/MainWindow.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace Cafe11
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        gr671_mkyuEntities entities;
        public MainWindow()
        {
            InitializeComponent();
            entities = new gr671_mkyuEntities();
        }

        private void btnlog_Click(object sender, RoutedEventArgs e)
        {
            if (string.IsNullOrWhiteSpace(txtlog.Text) || string.IsNullOrWhiteSpace(txtpass.Password))
            {
                MessageBox.Show("Поля не заполнены");
                return;
            }
            if (entities.Users.Select(x => x.Login + "" + x.Password).Contains(txtlog.Text + "" + txtpass.Password))
            {
                var role = entities.Users.Where(x => x.Login == txtlog.Text).Select(x => x.IdRole).FirstOrDefault();
                if (role == 1)
                {
                    povar pov = new povar();
                    pov.Show();
                    this.Close();
                }
                if (role == 2)
                {
                    ofic of = new ofic();
                    of.Show();
                    this.Close();
                }
                if (role == 3)
                {
                    admin ad = new admin();
                    ad.Show();
                    this.Close();
                }
            }
        }
    }
}