Recursive CTE with additional EXISTS conditions? - sql-server

Question

I have a situation where I need to be able to see if a given person is within a user/manager hierarchy.
I have the next structure of table:
UserId
UserName
ManagerId
I have 2 IDs: some UserId (say 5) and ManagerId (say 2). As a result I need to know if manager with given Id (2) is chief for user with given id (5)? For example, if
User 1 reports to user 2.
User 3 reports to user 1.
User 4 reports to user 3
the result SQL-query have to show that for UserId = 4 and ManagerId = 1 answer is true.
I've just created query for getting all hierarchy:
WITH temp (level, UserName, UserId, ManagerId) AS
(
SELECT 1 AS level, EmployeeName, EmployeeId, BossId
FROM Employees
WHERE BossId IS NULL
UNION ALL
SELECT level+1 AS level, EmployeeName, EmployeeId, BossId
FROM Employees, temp
WHERE BossId = UserId
)
SELECT t.* from temp AS t
But now I don't know how to get result query with above mentioned conditions :(
Thanks in advance for any help!

Answer 1

Find the user in the anchor and walk your way back up the hierarchy. Check the rows you have got in the recursive query against the manager.
This will return the manager row if there exist one.
WITH temp AS
(
SELECT EmployeeName, EmployeeId, BossId
FROM Employees
WHERE EmployeeId = #UserID
UNION ALL
SELECT E.EmployeeName, E.EmployeeId, E.BossId
FROM Employees AS E
inner join temp AS T
ON E.EmployeeId = T.BossId
)
SELECT *
FROM temp
WHERE EmployeeId = #ManagerID

Answer 2

This will return the BossID if he or she exist:
WITH BOSSES AS
(
SELECT BossID
FROM Employees
WHERE EmployeeID = #uID
UNION ALL
SELECT E.BossID
FROM Employees E
JOIN BOSSES B ON E.EmployeeID = B.BossID
)
SELECT *
FROM BOSSES
WHEN BossID = #bID

Answer 3

I've included the hierarchy of all levels with the CTE that you can then use to query. Using this hierarchy, you can see all the managers of a given employee in a delimited column (might be useful for other calculations).
Give this a try:
WITH cte (UserId, ManagerId, Level, Hierarchy) as (
SELECT EmployeeId, BossId, 0, CAST(EmployeeId as nvarchar)
FROM Employee
WHERE BossId IS NULL
UNION ALL
SELECT EmployeeId, BossId, Level+1,
CAST(cte.Hierarchy + '-' + CAST(EmployeeId as nvarchar) as nvarchar)
FROM Employee INNER JOIN cte ON Employee.BossId=cte.UserId
)
SELECT *
FROM cte
WHERE UserId = 4
AND '-' + Hierarchy LIKE '%-1-%'
And here is the Fiddle. I've used UserId = 4 and ManagerId = 1.
Good luck.