public lEnumerable GetList( int? parentID = null){ foreach ( var item in Context.TempTables .Where( x => x.ParentID == parentID ) .OrderBy( x=> x.SortOrder) .ToList() { yield return item; foreach( var child in GetList( item.ID)) { yield return child; } } } var sortedList = GetList(); 

它类似于您的方法，但它更小和递归。 适用于许多深度级别。 我更喜欢调用ToList，因为它会在查询下一个查询之前关闭结果集。

到目前为止，在单个查询中无法执行此操作。

请求单个查询

entity framework将自动填充所有孩子。

  public IEnumerable PrepareList(IEnumerable list){ list = list.OrderBy( x=> x.SortOrder); foreach(var item in list){ yield return item; foreach(var child in PrepareList(item.ChildTempTables)){ yield return child; } } } // since EF will automatically fill each children on fetch // all we need is just a top level nodes // which we will pass to PrepareList method var list = Context.TempTables.ToList().Where(x=> x.ParentID == null); var sortedList = PrepareList(list).ToList(); // it is good to create list at the end if you are going to // iterate it many times and logic will not change. 

这是一个非递归版本。 它不会在初始列表中一次又一次地迭代。 相反，它维护父子关系的字典，并将正在进行的预订树遍历的当前位置存储在枚举器中。

 public static IEnumerable PreorderForest(IEnumerable list) { var nodesByParent = list.GroupBy(x => x.ParentID.GetValueOrDefault(-1)) .ToDictionary(xs => xs.Key, xs => xs.OrderBy(x => x.SortOrder).GetEnumerator()); var stack = new Stack>(); stack.Push(nodesByParent[-1]); while (stack.Count > 0) { var nodes = stack.Peek(); if (nodes.MoveNext()) { yield return nodes.Current; IEnumerator children; if (nodesByParent.TryGetValue(nodes.Current.ID, out children)) stack.Push(children); } else stack.Pop(); } } 

实际上我不知道它是否可以通过优雅的LINQ查询。 这是DFS的递归版本，它构建查找以加快ParentID搜索速度

 public static IEnumerable SortedList(IEnumerable list = null, int? ParentID = null, ILookup lookup = null) { if (lookup == null) lookup = list.ToLookup(x => x.ParentID, x => x); foreach (var p in lookup[ParentID].OrderBy(x => x.SortOrder)) { yield return p; foreach (var c in SortedList(lookup: lookup, ParentID: p.ID)) yield return c; } } 

试试这个：

 public class Item { public int ID { get; set; } public int? ParentID { get; set; } public string Name { get; set; } public int SortOrder { get; set; } } public void DoWork() { Item[] data = new Item[] { new Item() { ID = 2, ParentID = 1, Name = "Test 2", SortOrder = 1}, new Item() { ID = 3, ParentID = 1, Name = "Test 3", SortOrder = 2}, new Item() { ID = 4, ParentID = 2, Name = "Test 4", SortOrder = 1}, new Item() { ID = 1, ParentID = null, Name = "Test 1", SortOrder = 1}, }; var result = from x in data orderby x.SortOrder, x.ParentID select x; foreach (var row in result.ToArray()) { Console.WriteLine(row.Name); } } 

我想这都是正确的订购

这是一个简单的解决方案：

 public class TempTable { public int ID {get;set;} public int? ParentID {get;set;} public String Name {get;set;} public int SortOrder {get;set;} } public List GetTempData() { var temp = new List(); temp.Add(new TempTable { ID = 1, ParentID = null, Name = "Test 1", SortOrder = 1 }); temp.Add(new TempTable { ID = 2, ParentID = 1, Name = "Test 2", SortOrder = 1 }); temp.Add(new TempTable { ID = 3, ParentID = 1, Name = "Test 3", SortOrder = 3 }); temp.Add(new TempTable { ID = 4, ParentID = 2, Name = "Test 4", SortOrder = 1 }); temp.Add(new TempTable { ID = 5, ParentID = 1, Name = "Test 5", SortOrder = 2 }); return temp; } 

用法：

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 var data = GetTempData(); var result = data.OrderBy(d => d.SortOrder).ThenBy(d => d.ParentID); //Do something with result