将联合查询转换为自我联接

Question

我正在尝试使用self join将此查询转换为一个查询。

SELECT leftn AS SId,
       TId
FROM test_tree
INNER JOIN
  (SELECT @sid:=
     (SELECT group_concat(leftn, ',', rightn)
      FROM test_tree
      WHERE find_in_set(sid, @nsid)) , @nsid:=@sid AS fset
   FROM test_tree,

     (SELECT @nsid:='AMSJUTATE',@sid='')v)gr ON find_in_set(leftn, fset)
WHERE leftn <> ''
UNION (
SELECT rightn AS SId,
       TId
FROM test_tree
INNER JOIN
  (SELECT @sid:=
     (SELECT group_concat(leftn, ',', rightn)
      FROM test_tree
      WHERE find_in_set(sid, @nsid)) , @nsid:=@sid AS fset
   FROM test_tree,

     (SELECT @nsid:='AMSJUTATE',@sid='')v)gr ON find_in_set(rightn, fset)
WHERE rightn <> ''

此查询表示父级有左子级和右子级，而我通过Union查找单个父级的所有子节点，但我想用另一种方式。有人可以转换此查询自我加入吗？我不知道如何转换此查询。

以下是我正在处理的数据的示例：

SELECT * FROM `test_tree`

TId SId         LeftN      RightN     LStatus RStatus   
1     -         AMSJUTATE               1       
2   AMSJUTATE   AMSNUDUCU   AMSFEZAVU   1   1   
3   AMSNUDUCU   AMSGUWUDE   AMSTUTUNE   1   1   
4   AMSFEZAVU   AMSXAWUXU   AMSHALURA   1   1   
5   AMSGUWUDE   AMSZUCIVO   AMSKEFOFA   1   1   
6   AMSTUTUNE   AMSFASOJA   AMSZAPUPE   1   1   
7   AMSXAWUXU   AMSTEMUJI   AMSPOROBE   1   1   
8   AMSHALURA   AMSBIZEZO   AMSFOHOFI   1   1   
9   AMSZUCIVO   AMSXUDINE               1       
10  AMSKEFOFA   AMSZEVUTA               1       
11  AMSFASOJA   AMSREXEGI               1       
12  AMSZAPUPE   AMSBIXIBO               1       
13  AMSTEMUJI   AMSHEFOVI               1       
14  AMSPOROBE   AMSLUPAKE               1       
15  AMSBIZEZO   AMSCUSIPU               1       
16  AMSFOHOFI   AMSCEMUSU               1       
17  AMSXUDINE   AMSKATOTU               1       
18  AMSZEVUTA   AMSLECEVU               1       
19  AMSREXEGI              AMSKOVUSA        1   
20  AMSBIXIBO              AMSLIWULO        1   
21  AMSHEFOVI              AMSJOLOWE        1   
22  AMSLUPAKE              AMSREROXE        1   
23  AMSCUSIPU              AMSPOMUBE        1   
24  AMSCEMUSU              AMSPULINU        1   
25  AMSPULINU              AMSWOFIVO        1