работает!!!

AutoService/Models/ProceedRepository.cs

@@ -19,7 +19,7 @@ namespace AutoService.Models
             try
             {
                 OpenConnection();
-                string sql1 = "INSERT INTO orders (id, client_name, car_model, service_id, total_amount, discount_percent, order_date) VALUES(0, @ClientName, @AutoModel, @ServiceId, @TotalAmount, @DiscountPercent, '@Date);";
+                string sql1 = "INSERT INTO orders (id, client_name, car_model, service_id, total_amount, discount_percent, order_date) VALUES(0, @ClientName, @AutoModel, @ServiceId, @TotalAmount, @DiscountPercent, @Date);";
                 string sql2 = "SELECT LAST_INSERT_ID() as id;";
                 string sql3 = "INSERT INTO auto_service_db.order_items (id, order_id, work_id, work_price) VALUES(0, @OrderId, @WorkId, @WorkPrice);";
                 using var transaction = connection.BeginTransaction();
@@ -37,9 +37,17 @@ namespace AutoService.Models
                         mc.ExecuteNonQuery();
                     }
                     using (var mc = new MySqlCommand(sql2, connection, transaction))
-                    using (var reader = mc.ExecuteReader())
                     {
-                        newId = reader.GetInt32("id");
+                        var result = mc.ExecuteScalar();
+                        if (result != null)
+                        {
+                            newId = Convert.ToInt32(result);
+                        }
+                        else
+                        {
+                            throw new Exception("Это печально всё");
+                        }
+
                     }
                     foreach (var work in works)
                     {

AutoService/ViewModels/ReceiptWindowVM.cs

@@ -1,6 +1,8 @@
 using AutoService.Models;
+using Avalonia.Controls;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
+using Microsoft.Extensions.DependencyInjection;
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
@@ -19,6 +21,8 @@ namespace AutoService.ViewModels
 
         private readonly IProceedRepository _proceedRepository;
 
+        public Button Btn { get; set; }
+
         [ObservableProperty]
         private ObservableCollection<Work> works;
 
@@ -63,8 +67,20 @@ namespace AutoService.ViewModels
                 TotalPrice=(int)TotalPrice
             };
             _proceedRepository.SaveOrder(Works, order);
+            Btn.IsEnabled = false;
 
         }
+        [RelayCommand]
+        public void ReturnToMain()
+        {
+            var vm = _serviceProvider.GetRequiredService<MainWindowVM>();
+            var win = _serviceProvider.GetRequiredService<MainWindow>();
+            win.DataContext = vm;
+            win.Show();
+            _currentWindow.Close();
+
+        }
+
 
         public void SetWindow(ReceiptWindow window)
         {

AutoService/ViewModels/WorksWindowVM.cs

@@ -52,6 +52,7 @@ namespace AutoService.ViewModels
             var win = _serviceProvider.GetRequiredService<ReceiptWindow>();
             win.DataContext = vm;
             vm.SetWindow(win);
+            vm.Btn = win.ProceedBtn;
             win.Show();
             _currentWindow.Close();
         }

AutoService/Views/ReceiptWindow.axaml

@@ -28,6 +28,8 @@
 			<TextBlock Text="Итого к оплате: "/>
 			<TextBlock Text="{Binding TotalPrice}"/>
         </StackPanel>
-        <Button Content="Подтвердить!" Command="{Binding ProceedTransactionCommand}"/>
+        <Button Content="Подтвердить!" Command="{Binding ProceedTransactionCommand}" x:Name="ProceedBtn"/>
+        <Button Content="Вернуться в окно выбора услуг" Command="{Binding ReturnToMainCommand}"/>
+
     </StackPanel>
 </Window>