如何更新的LINQ到SQL在Windows Phone應用程序

Question

記錄我用下面的代碼中插入新項目在購物車數據庫：

using (MFTDataContext Cartdb = new MFTDataContext(strConnectionString)) 
         { 
          Database InsertItemCart = new Database 
          { 
           ProductID = int.Parse(product_id[0]), 
           ProductName = product_name[0], 
           ProductPrice = int.Parse(product_price[0]), 
           ProductQuantity = singletonInstance.Quantity, 
           ProductTotalPrice = product_totalpriceINT, 
           ProductImageURL = product_image[0] 
          }; 


          Cartdb.MFTCart.InsertOnSubmit(InsertItemCart); 


          Cartdb.SubmitChanges(); 

現在什麼代碼，使用更新同一記錄。假設singletonInstance.Quantity從1更改爲5.現在如何更新相同的記錄。我不想創造新紀錄。如何更新相同記錄

Answer 1

private void Update(int itemID, int newQuantityValue) 
{ 
    using (var context = new YouContextType()) 
    { 
     var item = (from item in context.YourEntity 
        where item.ID == itemID 
        select item).Single(); 

     item.Quantity = newQuantityValue; 
     context.SubmitChanges(); 
    } 
}