Query to pick departments - sql

Question

I have a table like below:
Dept:
DeptName State Country
D1 Paris France
D2 Lyon France
D3 Lille France
Employee:
EmployeeId EmployeeName DeptName
1 John D1
2 Diesel D2
3 Rock D2
4 John D1
5 Diesel D2
6 Karn D2
7 Triple D1
8 Nancy D3
9 Greg D3
Output:
DeptName CountOfDifferentEmployeeName
D3 2
Get the department name and count of unique employee names for department using following conditions:
Pick only those department which have unique employee names in their country.There should not be same employee name in department in same country
While counting, avoid counting repeated employee names for the same department
But I am confused with whether I should do group by country and zoo name and how do I pick zoo name satisfying condition 1.
select * from Dept d
inner join Employee e on d.DeptName = e.DeptName
group by

Answer 1

If I get your requirement correct, this following script will help you to achieve your desired output-
DEMO HERE
SELECT D.DeptName,D.Country,
COUNT(E.EmployeeName) CountOfDifferentEmployeeName
FROM Employee E
iNNER JOIN Dept D ON E.DeptName = D.DeptName
GROUP BY D.DeptName,D.Country
HAVING COUNT(E.EmployeeName) = COUNT(DISTINCT E.EmployeeName)

Answer 2

I gather you want the names of department that don't have repeated employee name. If that is the case the query below is one way you can do it:
--1 Get per country all department that have repeated employee names
--2 Get the count per country and department of unique employee excluding the county department list in the cte
with Dept as
(
select 'D1' as DeptName, 'Paris' as State , 'France' as Country
union select 'D2' , 'Lyon' , 'France'
union select 'D3' , 'Lille' , 'France'
),
Employee as
(
select 1 as EmployeeId , 'John' as EmployeeName , 'D1' as DeptName
union select 2 , 'Diesel' , 'D2'
union select 3 , 'Rock' , 'D2'
union select 4 , 'John' , 'D1'
union select 5 , 'Diesel' , 'D2'
union select 6 , 'Karn' , 'D2'
union select 7 , 'Triple' , 'D1'
union select 8 , 'Nancy' , 'D3'
union select 9 , 'Greg' , 'D3'
)
select d.DeptName, d.Country, count(*) as unique_employee_names
from Dept d
inner join Employee e on d.DeptName = e.DeptName
where not exists
(
select 1
from (
select d.DeptName, d.Country
from Dept d
inner join Employee e on d.DeptName = e.DeptName
group by d.DeptName, d.Country, e.EmployeeName
having count(*) > 1
) c where d.DeptName = c.DeptName and d.Country = c.Country
)
group by d.DeptName, d.Country
Ouput is:
DeptName Country unique_employee_names
D3 France 2