單表一對多關系很常見，它是一種樹形結構，如系統菜單表，部門表，分類表，這些都可以做成單表一對多關系，而這些表做成一對多關系后，如果通過EntityFramework進行插入操作時，會很方便，EF會自動為我們確實上級ID，對于操作的性能也是可以接受的，與數據庫建立一次鏈接，發一批指定，這是我們可以接受的，雖然在性能上不是最佳的，但綜合對比來看，它即是最佳的。（結合對比＝程序性能+開發人員工時+程序擴展性+程序可讀性）

OK，我們以菜單表為例，說一下這個菜單表初始化的過程

對于菜單實體的賦值，看一下代碼：

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 ="系統管理",Operator = string.Empty,SortNumber = 1,Status = Status.Normal.GetHashCode(),UpdateDate = DateTime.Now,WebManageMenus1 = new List<WebManageMenus>{#region 二級菜單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 二級菜單new WebManageMenus{About = string.Empty,LinkUrl = string.Empty,MenuLevel = 2,MenuName ="部門管理",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 ="管理部門",Operator = string.Empty,SortNumber = 1,Status = Status.Normal.GetHashCode(),UpdateDate = DateTime.Now} }}, #endregion#region 二級菜單new WebManageMenus{About = string.Empty,LinkUrl = string.Empty,MenuLevel = 2,MenuName ="菜單管理",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 ="管理菜單管理",Operator = string.Empty,SortNumber = 1,Status = Status.Normal.GetHashCode(),UpdateDate = DateTime.Now} }}, #endregion#region 二級菜單new WebManageMenus{About = string.Empty,LinkUrl = string.Empty,MenuLevel = 2,MenuName ="員工管理",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 ="新建員工",Operator = string.Empty,SortNumber = 1,Status = Status.Normal.GetHashCode(),UpdateDate = DateTime.Now},new WebManageMenus{About = string.Empty,LinkUrl = "/User/Index",MenuLevel = 3,MenuName ="管理員工",Operator = string.Empty,SortNumber = 1,Status = Status.Normal.GetHashCode(),UpdateDate = DateTime.Now} }}, #endregion}}}};MenuRepository.Insert(menu);

我們可以看到，賦值的過程，我采用的EF生成的實體標準，對于子對象的賦值，我們可以看到,parentID并沒有賦值，因為這時它還沒不存在，這個parentID為上級

菜單的主鍵ID，所以EF在插入完父菜單后，會自動將ID賦值子對象的ParentID，這個過程是系統幫我們完成的。

對于上面的過程，所生成的SQL語句也是我們可以接受的

感謝您的閱讀，感謝Entity Framework開發團隊！

本文轉自博客園張占嶺（倉儲大叔）的博客，原文鏈接：EF架構~單表一對多集合的插入（樹型結構），如需轉載請自行聯系原博主。

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