--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;