LinqPad并没有更新更改的外键

Question

如果LINQPAD没有保存更改的外键，我该怎么办？ 以下代码不起作用：

var classScheduleToUpdate = ClassSchedules.First(x => x.Tp_classScheduleId == item.Tp_classScheduleId);
  classScheduleToUpdate.Tp_classId = lastInsertedId;
  SubmitChanges();

如果我将它复制到其他标签，硬编码一些ID并执行，那么一切正常。

完整代码如下。工作前后的一切都很好。

            void Main()
            {
                var classSchedules = ClassSchedules.Where(x => x.Active).GroupBy(x => new { x.Tp_classId, x.DayOfWeek }).Where(x => x.Count() > 1).ToList();
                foreach(var cs in classSchedules)
                {
                    int i=0;
                    foreach(var item in cs)
                    {
                        if(i == 0) { i++; continue; }
                        var newClass = new Classes()
                        {
                            Active = true,
                            ActiveFrom = item.Classes.ActiveFrom,
                            ActiveTo = item.Classes.ActiveTo,
                            Color = item.Classes.Color,
                            Name = item.Classes.Name,
                            Recommended = item.Classes.Recommended,
                            ClassDescription = item.Classes.ClassDescription,
                        };
                        Classes.InsertOnSubmit(newClass);
                        SubmitChanges();

                        int lastInsertedId = newClass.Tp_classId;

                        var classScheduleToUpdate = ClassSchedules.First(x => x.Tp_classScheduleId == item.Tp_classScheduleId);
                        classScheduleToUpdate.Tp_classId = lastInsertedId;
                        SubmitChanges();

                        foreach(var reservation in item.Reservations)
                            reservation.Tp_classId = lastInsertedId;
                        foreach(var cancellation in item.ClassSchedules_Cancellations)
                            cancellation.Tp_classId = lastInsertedId;
                        foreach(var rating in item.ClassRatings)
                            rating.Tp_classId = lastInsertedId;
                        foreach(var cccs in item.ClientClasses_ClassSchedules)
                            cccs.Tp_classId = lastInsertedId;
                        foreach(var entrance in item.SingleClientClassEntrances)
                            entrance.Tp_classId = lastInsertedId;
                        SubmitChanges();
                    }
                }
            }