2025-08-15 12:12:21 +0000 UTC

Primary Department for Each Employee
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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';