Find all ancestor nodes of a HierarchyId using a single SQL statement?
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16-10-2019 - |
Question
I'm trying to find a way to get all ancestor nodes of a given node using HierarchyID. Every solution I've seen using HierarchyID seems to use either a CTE or a variable. Is there a way to do this using a single select statement?
To make things simpler:
CREATE TABLE Employee
(
EmpId INT PRIMARY KEY IDENTITY,
EmpName VARCHAR(100) NOT NULL,
Position HierarchyID NOT NULL
)
INSERT INTO Employee (EmpName, Position)
VALUES ('CEO', '/'),
('COO', '/1/'),
('CIO', '/2/'),
('CFO', '/3/'),
('VP Financing', '/3/1/'),
('Accounts Receivable', '/3/1/1/'),
('Accountant 1', '/3/1/1/1/'),
('Accountant 2', '/3/1/1/2/'),
('Accountant 3', '/3/1/1/3/'),
('Accounts Payable', '/3/1/2/'),
('Accountant 4', '/3/1/2/1/'),
('Accountant 5', '/3/1/2/2/'),
('DBA', '/2/1/'),
('VP of Operations', '/1/1/')
Solution
To get "all parent nodes of a given node":
select *, position.GetAncestor(1), position.GetAncestor(1).ToString()
from employee
where position=hierarchyid::Parse('/3/1/')
EmpId EmpName Position (No column name) (No column name)
5 VP Financing 0x7AC0 0x78 /3/
but there will only ever be one due to the nature of hierarchies.
If you really want to get all immediate children nodes of a given node:
select *
from employee
where position.IsDescendantOf(hierarchyid::Parse('/3/1/'))=1
and position.GetLevel()=hierarchyid::Parse('/3/1/').GetLevel()+1
EmpId EmpName Position
6 Accounts Receivable 0x7AD6
10 Accounts Payable 0x7ADA
-- EDIT
I see that you want all ancestor nodes. Perhaps try an approach like this:
select *
from employee
where hierarchyid::Parse('/3/1/2/1/').IsDescendantOf(Position) = 1
or
select * from employee
where ( select position
from employee
where empname='Accountant 4' ).IsDescendantOf(Position) = 1
here is a CTE method for comparison:
with w as ( select * from employee where empname='Accountant 4'
union all
select e.*
from employee e join w on(w.position.GetAncestor(1)=e.Position) )
select * from w;
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