2025-08-15 15:12:21 +0300 MSK

Primary Department for Each Employee
Tags:

Code

SELECT 
    employee_id, 
    department_id
FROM 
    (
        SELECT 
            employee_id,
            department_id,
            primary_flag,
            COUNT(employee_id) OVER(
                PARTITION BY 
                    employee_id
            ) AS employee_count
        FROM 
            Employee
    ) EmployeePartition
WHERE 
    employee_count = 1 
    OR primary_flag = 'Y';