LINQ TO SQL 实现无限递归查询

现总结一下，希望能给以后再碰到此类问题的朋友一些帮助

 

--构造测试数据： 只作演示用CREATE TABLE [dbo].[Tim_LinqTable]([Id] int PRIMARY KEY IDENTITY(1,1) NOT NULL,[Name] [varchar](50) NOT NULL,[Parent] int NOT NULL,)GO INSERT INTO [Tim_LinqTable]  SELECT 'A',0 UNION ALLSELECT 'A1',1 UNION ALLSELECT 'A2',1 UNION ALLSELECT 'B1',2 UNION ALLSELECT 'B2',3 UNION ALLSELECT 'C1',4 UNION ALLSELECT 'C2',4 UNION ALLSELECT 'D1',5 UNION ALLSELECT 'D2',5 UNION ALLSELECT 'D3',5 GO WITH tempAS(SELECT * FROM [Tim_LinqTable]  WHERE Parent = 3UNION ALLSELECT m.* FROM [Tim_LinqTable]  AS mINNER JOIN temp AS child ON m.Parent = child.Id)SELECT * FROM tempGO --查询 Parent=3 的所有子数据结果如下:Id          Name                                               Parent----------- -------------------------------------------------- -----------5           B2                                                 38           D1                                                 59           D2                                                 510          D3                                                 5 (4 row(s) affected)

 

//好，下边来看看用C#怎么实现上边的SQL语句吧：void Main(){     var query=GetClassID(3);     Console.WriteLine("Id\tName\tParent");     query.ToList().ForEach(q=>Console.WriteLine("{0}\t{1}\t{2}",q.Id,q.Name,q.Parent));     /*        Id       Name       Parent        5        B2         3        8        D1         5        9        D2         5       10        D3         5     */}public IEnumerable
     
       GetClassID(int p_id){            var query = from c in this.Tim_LinqTables                        where c.Parent  == p_id                        select c;                    return  query.ToList().Concat(query.ToList().SelectMany(t => GetClassID(t.Id)));              }