单表一对多关系很常见，它是一种树形结构，如系统菜单表，部门表，分类表，这些都可以做成单表一对多关系，而这些表做成一对多关系后，如果通过EntityFramework进行插入操作时，会很方便，EF会自动为我们确实上级ID，对于操作的性能也是可以接受的，与数据库建立一次链接，发一批指定，这是我们可以接受的，虽然在性能上不是最佳的，但综合对比来看，它即是最佳的。（结合对比＝程序性能+开发人员工时+程序扩展性+程序可读性）
OK，我们以菜单表为例，说一下这个菜单表初始化的过程
对于菜单实体的赋值，看一下代码：
var menu = new WebManageMenus { About = string.Empty, LinkUrl = string.Empty, MenuLevel = 0, MenuName = form["MenuName"] ?? "根", Operator = string.Empty, ParentID = null, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now, WebManageMenus1 = new List<WebManageMenus> { new WebManageMenus { About = string.Empty, LinkUrl = string.Empty, MenuLevel = 1, MenuName ="系统管理", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now, WebManageMenus1 = new List<WebManageMenus> { #region 二级菜单 new WebManageMenus { About = string.Empty, LinkUrl = string.Empty, MenuLevel = 2, MenuName ="角色管理", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now, WebManageMenus1 = new List<WebManageMenus> { new WebManageMenus { About = string.Empty, LinkUrl = "/Role/Create", MenuLevel = 3, MenuName ="新建角色", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now }, new WebManageMenus { About = string.Empty, LinkUrl = "/Role/Index", MenuLevel = 3, MenuName ="管理角色", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now } } }, #endregion #region 二级菜单 new WebManageMenus { About = string.Empty, LinkUrl = string.Empty, MenuLevel = 2, MenuName ="部门管理", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now, WebManageMenus1 = new List<WebManageMenus> { new WebManageMenus { About = string.Empty, LinkUrl = "/Department/Index", MenuLevel = 3, MenuName ="管理部门", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now } } }, #endregion #region 二级菜单 new WebManageMenus { About = string.Empty, LinkUrl = string.Empty, MenuLevel = 2, MenuName ="菜单管理", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now, WebManageMenus1 = new List<WebManageMenus> { new WebManageMenus { About = string.Empty, LinkUrl = "/Menu/Index", MenuLevel = 3, MenuName ="管理菜单管理", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now } } }, #endregion #region 二级菜单 new WebManageMenus { About = string.Empty, LinkUrl = string.Empty, MenuLevel = 2, MenuName ="员工管理", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now, WebManageMenus1 = new List<WebManageMenus> { new WebManageMenus { About = string.Empty, LinkUrl = "/User/Create", MenuLevel = 3, MenuName ="新建员工", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now }, new WebManageMenus { About = string.Empty, LinkUrl = "/User/Index", MenuLevel = 3, MenuName ="管理员工", Operator = string.Empty, SortNumber = 1, Status = Status.Normal.GetHashCode(), UpdateDate = DateTime.Now } } }, #endregion } } } }; MenuRepository.Insert(menu);
我们可以看到，赋值的过程，我采用的EF生成的实体标准，对于子对象的赋值，我们可以看到,parentID并没有赋值，因为这时它还没不存在，这个parentID为上级
菜单的主键ID，所以EF在插入完父菜单后，会自动将ID赋值子对象的ParentID，这个过程是系统帮我们完成的。
对于上面的过程，所生成的SQL语句也是我们可以接受的
感谢您的阅读，感谢Entity Framework开发团队！