Question

我遇到了链接到SQL并更新记录的问题，我认为问题在于当前事务是基于我在循环连接数据上下文的事实：

    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

我收到错误的行是db.SaveChanges（），错误是“不允许新事务，因为会话中还有其他线程运行。”

Answer 1

不要认为你需要附加新对象，因为它已经存在。

db.lkpStores.Attach(newStore)

只需从ForEach循环更新商店对象，然后调用submit

   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

你也可以重构代码

   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

Answer 2

尝试将“Dim Stores = From b In db.lkpStores Where b.storeId ' = iStoreID ' Order By b.storeId”转换为List（），然后将其循环

LINQ-to-SQL更新查询

2 个答案: