I need to find multiple rows with iteration without using loop - sql-server

Question

Let's say I have 2 tables.
Users Table
and Have one more table which defines hierarchy of user.
hierarchy Table
So as you can see:
C is a supervisor of D
B is a supervisor of C
A is a supervisor of B
So when I pass User D, then it should return all the supervisor like A,B,C
same when I pass User C, then it should return all the supervisor like A,B
What I tried.
Create table Users
(
Id int primary key identity (1,1),
Name varchar(1),
)
Insert into Users values ('A')
Insert into Users values ('B')
Insert into Users values ('C')
Insert into Users values ('D')
Create table Hierarchy
(
Id int primary key identity (1,1),
EmployeeId int FOREIGN KEY REFERENCES Users(Id),
SupervisorId int FOREIGN KEY REFERENCES Users(Id)
)
Insert into Hierarchy values (4,3)
Insert into Hierarchy values (3,2)
Insert into Hierarchy values (2,1)
select * from Users
select * from Hierarchy
with HierarchyData as
(
select mbh.* from Hierarchy mbh where mbh.EmployeeId = 4
union all
select mbh.* from Hierarchy mbh
join Hierarchy on mbh.SupervisorId = Hierarchy.EmployeeId
where mbh.EmployeeId <> 4
)
select e.Name as EmpName, s.Name as SupervisorName from HierarchyData h
join Users e on h.EmployeeId = e.Id
join Users s on h.SupervisorId = s.Id
But I am getting only one level data.
Any kind of help would be appreciated.

Answer 1

#Vishal as per my understanding written query for you can you please check it's working or not?
here I used LEFT JOIN you can go with INNER JOIN
If you go with LEFT JOIN as per your example A not have any supervisor so the record can be empty.
If you go with INNER JOIN as per your example you got only the B, C, D record.
Please check the below test query.
DECLARE #User TABLE
(
UserID INT,
UserName NVARCHAR(50)
)
DECLARE #EmployeeTable TABLE
(
ID INT,
EmployeeID INT,
supervisorID INT
)
INSERT INTO #User VALUES(1,'A'),
(2,'B'),
(3,'C'),
(4,'D')
INSERT INTO #EmployeeTable VALUES
(1,4,3),
(2,3,2),
(3,2,1)
SELECT [U].[UserName] [EmployeeName],
[ET].[EmployeeID],
[ET].[SupervisorID],[ST].[SupervisorName]
FROM #User [U]
LEFT JOIN #EmployeeTable [ET]
ON [U].[UserID] = [ET].[EmployeeID]
LEFT JOIN
(
SELECT [U].UserName [SupervisorName] ,[ST].* FROM #User [U]
INNER JOIN #EmployeeTable [ST]
ON [ST].[supervisorID] = [U].[UserID]
) [ST]
ON [ST].[supervisorID] = [ET].[supervisorID]
Left join query result
Inner join query result
let me know if I can help more :).