Update a special id in hierarchical employee table - sql-server

Question

I have an update that has to be made. And Im really stuck.
This is a classic hierarchical employee table question, but with a twist.
Please look at this tree of users:
employees
(Completely unrelated to my problem, just something I found with google pictures)
Lets assume the following Id's:
RM1: EmpId 1, ParentId null
AM1: EmpId 2, ParentId 1
MGR1: EmpId 3, ParentId 2
MGR2: EmpId 4, ParentId 2
EMP1: EmpId 5, ParentId 3
EMP2: EmpId 6, ParentId 3
EMP3: EmpId 7, ParentId 4
EMP4: EmpId 8, ParentId 4
I need to add another column, lets call it parentSpecialId.
This id is the id of the user below root (AM1 and AM2).
All users below AM1 and AM2 should have the parentSpecialId set to the user below root.
Which gives us:
RM1: EmpId 1, ParentId null parentSpecialId null
AM1: EmpId 2, ParentId 1 parentSpecialId null
MGR1: EmpId 3, ParentId 2 parentSpecialId 2
MGR2: EmpId 4, ParentId 2 parentSpecialId 2
EMP1: EmpId 5, ParentId 3 parentSpecialId 2
EMP2: EmpId 6, ParentId 3 parentSpecialId 2
EMP3: EmpId 7, ParentId 4 parentSpecialId 2
EMP4: EmpId 8, ParentId 4 parentSpecialId 2
All I have is this CTE which gives me a result set with AM1 and AM2.
So I need to traverse all way down to EMPX and update parentSpecialId with Id 2 for
AM1 and the same for all users for AM2. Of course, it needs to by dynamic, in real life I have 12 of these users below root.
Does it make sense?
Here is my CTE:
WITH EmpsCTE AS
(
SELECT id, parent, name, 0 AS EmployeeLevel
FROM Employee
WHERE parent = 0
UNION ALL
SELECT e.id, e.parent, e.name, EmployeeLevel + 1
FROM EmpsCTE AS p
JOIN Employee AS e ON e.parent = p.id
)
SELECT id, parent, name, EmployeeLevel
From EmpsCTE where EmployeeLevel = 1
Oh, and I use Sql server 2008 R2

Answer 1

Sample data:
declare #T table
(
Name varchar(10),
EmpId int,
ParentId int,
ParentSpecialID int
);
insert into #T(Name, EmpId, ParentId) values
('RM1', 1, null),
('AM1', 2, 1),
('MGR1', 3, 2),
('MGR2', 4, 2),
('EMP1', 5, 3),
('EMP2', 6, 3),
('EMP3', 7, 4),
('EMP4', 8, 4);
Update statement:
with C as
(
select T3.EmpId,
T2.EmpId as ParentSpecialId
from #T as T1
inner join #T as T2
on T1.EmpId = T2.ParentId
inner join #T as T3
on T2.EmpId = T3.ParentId
where T1.ParentId is null
union all
select T.EmpId,
C.ParentSpecialId
from #T as T
inner join C
on T.ParentId = C.EmpId
)
update T
set ParentSpecialId = C.ParentSpecialId
from #T as T
inner join C
on T.EmpId = C.EmpId

Answer 2

To handle a tree of arbitrary depth:
declare #T table ( Name varchar(16), EmpId int, ParentId int );
insert into #T(Name, EmpId, ParentId) values
('RM1', 1, null),
('AM1', 2, 1),
('MGR1', 3, 2),
('MGR2', 4, 2),
('EMP1', 5, 3),
('EMP2', 6, 3),
('EMP3', 7, 4),
('EMP4', 8, 4),
('AM2', 9, 1),
('MGR3', 10, 9),
('EMP5', 11, 10),
('Brown Noser', 12, 11),
('Intern', 13, 12),
('Coop', 14, 13),
('Nephew', 15, 14),
('Contractor', 16, 15);
; with CTE as (
-- Start with the root(s).
select Name, EmpId, ParentId, 0 as Depth, Cast(NULL as Int) as parentSpecialId
from #T
where ParentId is NULL
union all
-- Add the direct reports one layer at a time.
select T.Name, T.EmpId, T.ParentId, CTE.Depth + 1, case when CTE.Depth = 1 then T.ParentId else CTE.parentSpecialId end
from CTE inner join
#T as T on T.ParentId = CTE.EmpID
where T.ParentId = CTE.EmpId
)
select *,
( select Name from CTE as R where R.EmpId = CTE.ParentId ) as ReportsTo,
( select Name from CTE as SC where SC.EmpId = CTE.parentSpecialId ) as SubCommander
from CTE
order by Depth, Name
With thanks to Mikael Eriksson for setting up the sample data!