Find Oldest Employee per Department Query

Question

Find the oldest employee in each department based on hire date.

Accepted Answer

```sql
SELECT department_id, name, hire_date
FROM employees e1
WHERE hire_date = (
    SELECT MIN(hire_date)
    FROM employees e2
    WHERE e1.department_id = e2.department_id
);
```

This query uses a correlated subquery to identify the minimum `hire_date` for each `department_id` and returns the corresponding employee records.