如何在SQL Server中简化此SQL查询？

我正在尝试获取父子层次结构。这是我的查询，如果有任何方法可以简化它…仅使用此查询

SELECT   
    Chain0.ParId AS ParentId, 
    CASE
       WHEN Chain3.title <> ' '
          THEN Chain3.title + ' > ' + Chain2.title + ' > ' + Chain1.title + ' > ' + Chain0.title
       WHEN Chain2.title <> ' '
          THEN Chain2.title + ' > ' + Chain1.title + ' > ' + Chain0.title
       WHEN Chain1.title <> ''
          THEN Chain1.title + ' > ' + Chain0.title
       WHEN Chain0.title <> ' '
          THEN Chain0.title
    END AS title
FROM 
    (SELECT 
         T1.Id, T1.Title, T2.ParId  
     FROM 
         TestTable as T1 
     LEFT OUTER JOIN 
         TestTable2 as T2 ON T1.Id = T2.Id) Chain0
LEFT OUTER JOIN 
    (SELECT 
         T1.Id, T1.Title, T2.ParId  
     FROM 
         TestTable as T1 
     LEFT OUTER JOIN 
         TestTable as T2 ON T1.Id = T2.Id) Chain1 ON Chain0.ParId = Chain1.Id
LEFT OUTER JOIN 
    (SELECT 
         T1.Id, T1.Title, T2.ParId  
     FROM 
         TestTable as T1 
     LEFT OUTER JOIN 
         TestTable as T2 ON T1.Id = T2.Id) Chain2 ON Chain1.ParId = Chain2.Id
LEFT OUTER JOIN 
    (SELECT 
         T1.Id, T1.Title, T2.ParId  
     FROM 
         TestTable as T1 
     LEFT OUTER JOIN 
         TestTable as T2 ON T1.Id = T2.Id) Chain3 ON Chain2.ParId = Chain3.Id
LEFT OUTER JOIN 
    (SELECT 
         T1.Id, T1.Title, T2.ParId  
     FROM 
         TestTable as T1 
     LEFT OUTER JOIN 
         TestTable as T2 ON T1.Id = T2.Id) Chain4 ON Chain3.ParId = Chain4.Id   

输出：

ParentId    title
---------------------------
NULL        test
  1         test > get
  2         test > get > this
  3         test > get > this > value

简化这个查询我需要像上面这样的格式输出…

这是通过

这是通过

---

您可以共享表结构和一些示例数据吗？id title 1 test 2 get 3 this 4 value id text parId 1 test1 null 2 get1 3 this1 2 4 value1 3请不要将代码示例或示例数据放入注释中-因为您无法格式化它，所以读取它非常困难。。。。取而代之的是：通过编辑你的问题来更新它，以提供额外的信息！谢谢。示例中有一个输入错误：它必须是“TestTable2 as T2”在整个查询过程中。您可以共享表结构和一些示例数据吗？id title 1 test 2 get 3 this 4 value id text parId 1 test1 null 2 get1 1 3 this 1 2 4 value1 3请不要将代码示例或示例数据放入注释中-因为您无法格式化它，所以读取它非常困难。。。。取而代之的是：通过编辑你的问题来更新它，以提供额外的信息！谢谢。示例中有一个输入错误：在整个查询过程中，它必须是“TestTable2 as T2”。很有可能，尽管不知道为什么？那么您真的应该使用递归。当然，您可以根据需要复制最后一个查询中的行。使用相应的Ref5、6和7来访问Src5、6和7是非常简单的。这是很可能的，尽管不知道为什么？那么您真的应该使用递归。当然，您可以根据需要复制最后一个查询中的行。通过相应的参考文献5、6和7，可以非常直接地访问Src5、6和7。

ParentId    title
---------------------------
NULL        test
  1         test > get
  2         test > get > this
  3         test > get > this > value

With
TestTable (id, title) As (
    Select 1, 'test' Union All
    Select 2, 'get'  Union All
    Select 3 ,'this' Union All
    Select 4, 'value'
    ),
TestTable2 (id, text, parId) As (
    Select 1, 'test1' , null Union All
    Select 2, 'get1'  , 1    Union All
    Select 3, 'this1' , 2    Union All
    Select 4, 'value1', 3
    ),
RecursiveCTE As (
    Select
        Src.id,
        Ref.parId,
        CAST(Src.title As varchar(1024)) As title --< Types in the Union must be aligned
    From TestTable Src
    Inner Join TestTable2 Ref On Src.id = Ref.id AND Ref.parId Is NULL
    Union All
    Select
        Src.id,
        Ref.parId,
        CAST(Prev.title + ' > ' + Src.title As varchar(1024)) As title --<   ... aligned
    From TestTable Src
    Inner Join TestTable2 Ref On Src.id = Ref.id
    Inner Join RecursiveCTE Prev On Prev.id = Ref.parId --<       Recursive call to self
)
Select parId As ParentId, title From RecursiveCTE

With
TestTable (id, title) As (
    Select 1, 'test' Union All
    Select 2, 'get'  Union All
    Select 3 ,'this' Union All
    Select 4, 'value'
    ),
TestTable2 (id, text, parId) As (
    Select 1, 'test1' , null Union All
    Select 2, 'get1'  , 1    Union All
    Select 3, 'this1' , 2    Union All
    Select 4, 'value1', 3
    )
Select
    Ref1.parID As ParentId,
    COALESCE(Src4.title + ' > ', '') +
    COALESCE(Src3.title + ' > ', '') +
    COALESCE(Src2.title + ' > ', '') +
    Src1.title As title
From TestTable2 Ref1
Left Join TestTable2 Ref2 On Ref2.id = Ref1.parId
Left Join TestTable2 Ref3 On Ref3.id = Ref2.parId
Left Join TestTable2 Ref4 On Ref4.id = Ref3.parId
Left Join TestTable Src1 On Src1.id = Ref1.id
Left Join TestTable Src2 On Src2.id = Ref2.id
Left Join TestTable Src3 On Src3.id = Ref3.id
Left Join TestTable Src4 On Src4.id = Ref4.id