--1
SELECT e.first_name , e.last_name, j.JOB_TITLE
FROM EMPLOYEES e JOIN jobs j USING(job_id);

--2
SELECT  DISTINCT COUNT(e.first_name)
FROM EMPLOYEES e JOIN jobs j USING(job_id)
WHERE j.JOB_TITLE = 'Sales Manager';

--3
SELECT e.first_name, e.last_name, TO_CHAR(e.hire_date,'yyyy/month')
FROM EMPLOYEES e;

--4
--5
--6
--7
SELECT COUNT(e.EMPLOYEE_ID ), d.DEPARTMENT_NAME
FROM EMPLOYEES e JOIN DEPARTMENTS d ON e.DEPARTMENT_ID = d.DEPARTMENT_ID
WHERE TO_CHAR(e.HIRE_DATE,'yyyy')IN ('2005','2006') 
GROUP BY d.DEPARTMENT_NAME
ORDER BY 2;

--8
--9
SELECT d.DEPARTMENT_NAME, e.FIRST_NAME, e.LAST_NAME
FROM DEPARTMENTS d JOIN EMPLOYEES e ON d.DEPARTMENT_ID = e.DEPARTMENT_ID
WHERE e.JOB_ID NOT LIKE '%IT%';

--10
SELECT COUNT(e.EMPLOYEE_ID), j.JOB_TITLE
FROM JOBS j JOIN EMPLOYEES e ON j.JOB_ID = e.JOB_ID
WHERE TO_CHAR(e.HIRE_DATE,'MM') IN (1,2,3)
GROUP BY j.JOB_TITLE;

--11
SELECT d.DEPARTMENT_NAME, l.CITY, c.COUNTRY_NAME
FROM DEPARTMENT d JOIN LOCATIONS l ON d.LOCATION_ID = l.LOCATION_ID
JOIN HR.COUNTRIES  c ON  c.COUNTRY_ID=l.COUNTRY_ID;