如何使用sybase ase 12.5用一个SQL查询检索树数据？

Question

suppose I have a tree data stored in mytab with id, parentid, then I want to get all parents for each id in one query. For example, a binary tree like(node 1 parent is null):

           1
    11          12

111    112   121   122

for any node, find out all parents with parent level(from bottom to top).

for example, node 111: I want to have data like:

id parentid level
111    11       1    
11     1        2

for node 11, I want to have data like:

id parentid level
111    11       1    

for node 121, I want to have data like:

id parentid level
121    12       1    
12     1        2

and so on. Without cursor with loop, how to get it in one query(maybe a recursive query)?

the depth of the tree could be more than 100. so recursive proc/trigger also not working as ase 12.5 nest level limit is 16.

Answer 1

Something like this:

DECLARE @id int = 111

;WITH CTE
AS
(
  SELECT Id, ParentId, 1 as level FROM tbl WHERE Id = @id
  UNION ALL
  SELECT T2.Id, T2.ParentId, T1.level + 1 FROM CTE T1 
    JOIN tbl T2 ON T1.ParentId = T2.Id  
)

SELECT * FROM CTE WHERE ParentId IS NOT NULL