Code must edit cell but it edits an duplicates

internal static void EditProduct(string txtBarCode, string txtArtNumber, string txtProductName, string txtPrice, string txtComment, decimal NumericUpDown1, string PriceWithOutAWD, string txtSelfPrice)
       {
           SqlConnection con = new SqlConnection(ConnectionString);
           SqlCommand cmd = new SqlCommand("UPDATE Products SET BarCode = @BarCode, ArtNumber = @ArtNumber, ProductName = @ProductName, Price = @Price, SelfPrice = @SelfPrice, PriceWithOutAWD = @PriceWithOutAWD, UnitsInStock = @UnitsInStock, Comment = @Comment WHERE BarCode = @bc AND ArtNumber = @an ", con);


           cmd.Parameters.Add(new SqlParameter("@BarCode", txtBarCode));
           cmd.Parameters.Add(new SqlParameter("@ArtNumber", txtArtNumber));
           cmd.Parameters.Add(new SqlParameter("@ProductName", txtProductName));
           cmd.Parameters.Add(new SqlParameter("@Price", txtPrice));
           cmd.Parameters.Add(new SqlParameter("@SelfPrice", txtSelfPrice));
           cmd.Parameters.Add(new SqlParameter("@PriceWithOutAWD", PriceWithOutAWD));
           cmd.Parameters.Add(new SqlParameter("@UnitsInStock", NumericUpDown1));
           cmd.Parameters.Add(new SqlParameter("@Comment", txtComment));
           cmd.Parameters.Add(new SqlParameter("@bc", txtBarCode));
           cmd.Parameters.Add(new SqlParameter("@an", txtArtNumber));
           try
           {
               con.Open();
               cmd.ExecuteNonQuery();
           }
           finally
           {
               con.Close();
           }
       }