--1
select MAX(salary) "Maximum", MIN(salary) min, AVG(salary) group_avg, SUM(salary) "Total_Salary", count (*) as pracownikow
FROM emp
--2
SELECT MIN(last_name), MAX(last_name)
from emp
--3
SELECT count(*) as "liczba pracowniukow"
from emp
where commission_pct != 0 and dept_id = 31
--4
SELECT credit_rating, count(*) as lizcba
from customer
GROUP BY credit_rating a
--5
SELECT title, SUM(salary) AS laczne_zarobki
FROM emp
WHERE title NOT LIKE '%VP%'
GROUP BY title
ORDER BY laczne_zarobki ASC;