SELECT employee_name
FROM employees
WHERE department_id = 102
ORDER BY birth_year ASC
LIMIT 1;

2. Identifying the Lowest Paid Employee in Finance Department

SELECT employee_name
FROM employees
WHERE department_id = 101
ORDER BY salary ASC
LIMIT 1;

3. Departments with Total Salaries Exceeeding 9000

SELECT d.department_name
FROM departments d
INNER JOIN employees e ON d.department_id = e.department_id
GROUP BY d.department_id
HAVING SUM(e.salary) > 9000;

4. Highest Age Emploeye with Salary Between 7500 and 8500

SELECT e.employee_name, d.department_name
FROM employees e
INNER JOIN departments d ON e.department_id = d.department_id
WHERE e.salary BETWEEN 7500 AND 8500
ORDER BY e.birth_year ASC
LIMIT 1;

5. Hire Date of Lowest Paid Sales Department Employee

SELECT hire_date
FROM employees
WHERE department_id = 102
ORDER BY salary ASC
LIMIT 1;

6. Finance Department Employees Earning Over 2000

SELECT employee_name
FROM employees
WHERE department_id = 101 AND salary > 2000;

7. Average Salary by Department

SELECT d.department_name, AVG(e.salary) AS average_salary
FROM employees e
INNER JOIN departments d ON e.department_id = d.department_id
GROUP BY d.department_id;

8. Employee IDs in IT Department

SELECT employee_id
FROM employees
WHERE department_id = 103;

9. Total Salary Expenditure in Finance Department

SELECT SUM(salary) AS total_salary
FROM employees
WHERE department_id = 101;

10. Departments Without Employees

SELECT d.department_id, d.department_name
FROM departments d
LEFT JOIN employees e ON d.department_id = e.department_id
GROUP BY d.department_id
HAVING COUNT(e.employee_id) = 0;

11. Departments with Employees Earning Above 7000

SELECT d.department_id, d.department_name
FROM departments d
INNER JOIN employees e ON d.department_id = e.department_id
GROUP BY d.department_id
HAVING MAX(e.salary) > 7000;

12. Total Salary Expedniture by Department

SELECT d.department_name, SUM(e.salary) AS department_total
FROM employees e
INNER JOIN departments d ON e.department_id = d.department_id
GROUP BY d.department_id;

13. Oldest Employee in Each Department

SELECT e.employee_name, d.department_name
FROM employees e
INNER JOIN departments d ON e.department_id = d.department_id
GROUP BY d.department_id
ORDER BY d.department_id, e.birth_year ASC;

14. Salary and Department for Employee 'Li Si'

SELECT salary, d.department_name
FROM employees e
INNER JOIN departments d ON e.department_id = d.department_id
WHERE e.employee_name = 'Li Si';

15. Highest Paid Employees by Department

SELECT e.employee_name, d.department_name, e.salary
FROM employees e
INNER JOIN departments d ON e.department_id = d.department_id
WHERE e.salary = (
  SELECT MAX(e2.salary)
  FROM employees e2
  WHERE e2.department_id = e.department_id
)
ORDER BY e.salary DESC;