sql – CTE遍历备份层次结构？

我可以在分层数据模型中找到给定记录的所有子项(请参阅下面的代码),但是我不知道如何通过给定的子代码来备份父/子链.任何人都可以指出正确的方向,找出如何做到这一点？在 Linq到sql中也是可能的吗？

WITH TaskHierarchy (TaskID,[Subject],ParentID,HierarchyLevel,HierarchyPath) AS
(
   -- Base case
   SELECT
      TaskID,1 as HierarchyLevel,CONVERT(VARCHAR(MAX),'/') AS HierarchyPath
   FROM Task
   WHERE TaskID = 2

   UNION ALL

   -- Recursive step
   SELECT
      t.TaskID,t.Subject,t.ParentID,th.HierarchyLevel + 1 AS HierarchyLevel,CONVERT(varchar(MAX),th.HierarchyPath + CONVERT(VARCHAR(32),t.ParentID) + '/') AS HierarchyPath
   FROM Task t
      INNER JOIN TaskHierarchy th ON
         t.ParentID = th.TaskID
)

SELECT *
FROM TaskHierarchy
ORDER BY HierarchyLevel,[Subject]

解决方法

啊,我想出来了

WITH Hierarchy(TaskID,IsProject,HLevel)
AS
(
    SELECT 
        TaskID,0 as HLevel
    FROM 
        Task 
    WHERE 
        TaskID = 59

    UNION ALL

    SELECT 
        SubDepartment.TaskID,SubDepartment.[Subject],SubDepartment.ParentID,SubDepartment.IsProject,HLevel + 1
    FROM 
        Task SubDepartment
    INNER JOIN 
        Hierarchy ParentDepartment
    ON 
        SubDepartment.TaskID = ParentDepartment.ParentID 
)

SELECT 
    TaskID,HLevel
FROM  
    Hierarchy
ORDER BY
    HLevel DESC

原文地址：https://www.jb51.cc/mssql/82141.html