G-3130: Try to use ANSI SQL-92 join syntax.
ANSI SQL-92 join syntax supports the full outer join. A further advantage of the ANSI SQL-92 join syntax is the separation of the join condition from the query filters.
SELECT e.employee_id ,e.last_name ,e.first_name ,d.department_name FROM employees e ,departments d WHERE e.department_id = d.department_id AND EXTRACT(MONTH FROM e.hire_date) = EXTRACT(MONTH FROM SYSDATE);
SELECT emp.employee_id ,emp.last_name ,emp.first_name ,dept.department_name FROM employees emp JOIN departments dept ON dept.department_id = emp.department_id WHERE EXTRACT(MONTH FROM emp.hire_date) = EXTRACT(MONTH FROM SYSDATE);