skontrolovali by ste mi toto prosim, ci to mam OK ?
select department_name, city, count(*)
from hr.employees OUTER join hr.departments using (department_id) join hr.locations using (location_id)
where city like 'Seattle'
group by department_name, city
having count(*)>=1 AND count(*)<=4
order by 3;
MV1 <- employees OUTER JOIN department_id=department_id departments
MV2 <- MV1 JOIN location_id=location_id locations
MV3 <- sigma city like 'Seattle' (MV2)
MV4(department_name, city, pocet) <- department_name, city, F count employee_id (MV3)
V(department_name, city, pocet) <- sigma pocet between 1 and 4 (MV4)