Notes

select * from countries;
select * from locations;
select * from employees;
select * from jobs;
select * from departments;
select * from job_history;

--1--
select location_id, street_address, city, state_province, country_name
from locations natural join countries;

--2--
select last_name, department_id, department_name
from employees natural join departments;

--3--
select e.last_name, e.job_id, e.department_id, d.department_name
from employees e join departments d
on d.department_id = e.department_id
join locations l
on city = 'Toronto';

--4--
select e.last_name Employee, e.employee_id as emp#, m.last_name Manager, m.employee_id mgr#
from employees e join employees m
on (e.manager_id = m.employee_id);

--5--
select e.last_name Employee, e.employee_id as emp#, m.last_name Manager, m.employee_id mgr#
from employees e left outer join employees m
on (e.manager_id = m.employee_id)
order by e.employee_id;

--6--
select e.department_id Department, c.last_name Colleague, e.last_name Employee
from employees e join employees c on ( e.department_id = c.department_id)
where c.last_name != e.last_name
order by e.department_id;

--7--
select last_name, job_id, department_name, salary
from employees e join departments d
on e.department_id=d.department_id
order by salary;

--8--
select last_name, hire_date
from employees
--where hire_date > '29-JAN-05'
where hire_date > (select hire_date from employees where last_name = 'Davies')
order by hire_date;

--9--
select e.last_name, e.hire_date, m.last_name, m.hire_date
from employees e join employees m
on e.manager_id = m.employee_id
where e.hire_date < m.hire_date;