SELECT DISTINCT EMPLOYEE.NAME, EMPLOYEE.POSITION FROM EMPLOYEE WHERE EMPLOYEE.DEPARTMENT_ID=[Введите интересующий отдел];

SELECT EMPLOYEE.NAME FROM EMPLOYEE
JOIN (SELECT CHIEF_ID, AVG(SALARY) AS S FROM EMPLOYEE WHERE CHIEF_ID IS NOT NULL
GROUP BY CHIEF_ID) AS T ON EMPLOYEE.ID = T.CHIEF_ID
WHERE EMPLOYEE.SALARY > (T.S * 2)