List to ObservableCollection with INotifyPropertyChanged

Hi Guys,

i have the following Property:

public ObservableCollection List
{
get
{
if (list.Count == 0)
{
// query database and return list
List tempList = QueryDataBase();
list = new ObservableCollection(list);
}
return list;
}
set
{
list= value;
}
}

Now when a item changes in 'list' i want the notifypropertychanged event to be called.

Any ideas on how i can handle this?

I cant change the returntype of QueryDataBase() to be an ObservableCollection.

Thanks