如何在LINQ to SQL中删除然后添加子项

Question

我有一系列儿童用品,我不想删除,然后添加新的.
我不关心性能,因为它是一种非常频繁的操作.

我该怎么办？我试过了Order.items.clear(),Order.Items.Remove(x)但都给了我例外

简化代码:

    Dim db As New MainDataDataContext
    dim o as Order = (From Order In db.Orders Where Order.OrderID = OrderID).FirstOrDefault
    ''//this will return "An attempt was made to remove a 
    ''//relationship between a Order and a OrderItem. 
    ''//However, one of the relationship's foreign keys 
    ''//(Order.OrderID) cannot be set to null." exception
    o.Items.Clear()
    ''//and this will return "EntitySet was modified during enumeration." exception
    For Each oItem As OrderItem In o.Items
        o.items.Remove(oItem)
    Next

    For Each item As ListViewItem In listViewOrderItems.Items
        If item.ItemType = ListViewItemType.DataItem Then
            Dim oItem As New OrderItem
            oItem.OrderID = OrderID
            oItem.Product = CType(item.FindControl("txtProduct"), TextBox).Text
            oItem.Quantity = CType(item.FindControl("txtQuantity"), TextBox).Text
            Order.items.Add(oItem)
        End If
    Next

    db.SubmitChanges()

Answer 1

只要您删除所有项目,您也可以使用

db.OrderItems.DeleteAllOnSubmit(o.Items);