LINQ到SQL更新查詢

Question

我遇到鏈接到SQL和更新記錄的問題，我認爲問題是與當前事務的基礎上，我通過連接的數據上下文循環：

Using db = New PostcodeLookupModelContainer() 

     Dim Stores = From b In db.lkpStores Where b.storeId ' = iStoreID ' Order By b.storeId 

     For Each store In Stores 

      Debug.Print(store.StorePostcode) 

      Dim newStore As New lkpStores() 
      newStore.depotId = store.depotId 
      newStore.StorePostcode = store.StorePostcode 
      newStore.depotId = store.depotId 
      newStore.DepotDistance = store.DepotDistance 

      db.lkpStores.Attach(newStore) 
      newStore.DepotDistance = 50 

      db.SaveChanges() 

     Next store 

    End Using 

當我得到錯誤的行是db.SaveChanges（），錯誤是'新的事務是不允許的，因爲會話中有其他線程正在運行'。

Answer 1

嘗試轉換你的 「Dim Stores = From b In db.lkpStores Where b.storeId ' = iStoreID ' Order By b.storeId」 到列表（）然後循環它

Answer 2

不要以爲你需要附加新的對象，因爲它已經存在。

db.lkpStores.Attach(newStore) 

只需更新從foreach循環的存儲對象，並調用提交

Using db = New PostcodeLookupModelContainer() 

     Dim Stores = From b In db.lkpStores Where b.storeId ' = iStoreID ' Order By b.storeId 

     For Each store In Stores 
      store.DepotDistance = 50 
      db.SaveChanges() 
     Next store 

    End Using 

你也可以重構代碼

Using db = New PostcodeLookupModelContainer() 

     Dim store = (From b In db.lkpStores Where b.storeId).SingleOrDefault 'Assumming the storeID is unique 

     if store isnot nothing then 
      store.DepotDistance = 50 
      db.SaveChanges() 
     end if 

    End Using