Getting List of Employees under Head and sub heads - sql

Question

I want to get a list of employees who come under the given Head/Employee.
It should return all sub-heads and their sub-head and employees under him/her.
Following is the list of all Employees with their designations.
EmpID
Name
Designation
HeadEmpID
1
CEO
1
0
2
CountryHead-USA
2
1
3
CountryHead-UK
2
1
4
StateHead-USA-A
3
2
5
StateHead-USA-B
3
2
6
StateHead-UK-C
3
3
7
ZoneHead-A
9
6
8
ZoneHead-B
9
6
9
ZoneHead-C
9
4
10
CityHead-A
12
7
Lets say we ask Who comes under 'CountryHead-UK'?
It should return
EmpID
Name
Designation
Head
3
CountryHead-UK
2
1
6
StateHead-UK-C
3
3
7
ZoneHead-A
9
6
8
ZoneHead-B
9
6
10
CityHead-A
12
7
If we ask who should come under CEO, then it should return everyone (for this sample data)
DROP TABLE IF EXISTS #A
CREATE TABLE #A (EmpID int,Name VARCHAR(MAX), Designation INT, HeadEmpID INT)
INSERT INTO #A VALUES (1,'CEO',1,0)
INSERT INTO #A VALUES (2,'CountryHead-USA',2,1)
INSERT INTO #A VALUES (3,'CountryHead-UK',2,1)
INSERT INTO #A VALUES (4,'StateHead-USA-A',3,2)
INSERT INTO #A VALUES (5,'StateHead-USA-B',3,2)
INSERT INTO #A VALUES (6,'StateHead-UK-C',3,3)
INSERT INTO #A VALUES (7,'ZoneHead-A',9,6)
INSERT INTO #A VALUES (8,'ZoneHead-B',9,6)
INSERT INTO #A VALUES (9,'ZoneHead-C',9,4)
INSERT INTO #A VALUES (10,'CityHead-A',12,7)
SELECT * FROM #A a
Fiddle: https://dbfiddle.uk/YZH65Xvi

Answer 1

Thanks Larnu for a hint.
Follwing worked.
with cte as (
select e.Empid, e.Name, e.Head, b.Name N1, b.Head new_boss
from #a e
left join #a b on b.Empid = e.Head
union all
select c.Empid, c.Name, c.new_boss, e.name, e.head
from cte c
join #a e on e.Empid = c.new_boss
)
select Empid, Name, Head, N1
from cte WHERE n1 = 'CountryHead-UK'
order by Empid, head