небольшой фикс

GasStation/Entities/Selling.cs

@@ -6,19 +6,16 @@ public class Selling
 
     public int GasmanId { get; private set; }
 
-    public int Count { get; private set; }
-
     public IEnumerable<ProductSelling> ProdutcSellings { get; private set; } = [];
 
     public DateTime SellingDateTime { get; private set; }
 
-    public static Selling CreateSelling(int id, int gasmanId, int count, IEnumerable<ProductSelling> produtcSellings)
+    public static Selling CreateSelling(int id, int gasmanId, IEnumerable<ProductSelling> produtcSellings)
     {
         return new Selling
         {
             Id = id,
             GasmanId = gasmanId,
-            Count = count,
             SellingDateTime = DateTime.Now,
             ProdutcSellings = produtcSellings
         };

GasStation/Forms/FormProduct.cs

@@ -31,7 +31,7 @@ public partial class FormProduct : Form
                 {
                     throw new InvalidDataException(nameof(product));
                 }
-
+                numericUpDownCost.Value = product.ProductCost;
                 comboBoxProduct.SelectedItem = product.ProductType;
                 _productId = value;
             }

GasStation/Forms/FormSelling.cs

@@ -33,8 +33,8 @@ namespace GasStation.Forms
                     throw new Exception("Имеются незаполненые поля");
                 }
 
-                _sellingRepository.CreateSelling(Selling.CreateSelling(0, (int)comboBoxGasman.SelectedValue!,
-                    0, CreateProductSellingsFromDataGrid()));
+                _sellingRepository.CreateSelling(Selling.CreateSelling(0, (int)comboBoxGasman.SelectedValue!
+                    , CreateProductSellingsFromDataGrid()));
 
                 Close();
             }

GasStation/Repositories/Implementations/SellingRepository.cs

@@ -29,8 +29,8 @@ public class SellingRepository : ISellingRepository
             connection.Open();
             using var transaction = connection.BeginTransaction();
             var queryInsert = @"
-INSERT INTO selling (sellingDateTime, gasmanId, count)
-VALUES (@SellingDateTime, @GasmanId, @Count);
+INSERT INTO selling (sellingDateTime, gasmanId)
+VALUES (@SellingDateTime, @GasmanId);
 SELECT MAX(Id) FROM selling";
             var Id = connection.QueryFirst<int>(queryInsert, selling, transaction);
             var querySubInsert = @"