--SELECT * FROM os_udaje, student WHERE student.rod_cislo = os_udaje.rod_cislo
--SELECT meno, priezvisko FROM student NATURAL JOIN os_udaje WHERE rocnik = 2
--SELECT meno, priezvisko FROM os_udaje WHERE substr(rod_cislo,1,2) BETWEEN 85 AND 89
--SELECT meno, priezvisko FROM os_udaje NATURAL JOIN student NATURAL JOIN zap_predmety WHERE zap_predmety.cis_predm = 'BI06' AND zap_predmety.vysledok IS NULL ORDER BY meno ASC
--SELECT prednasajuci, cis_predm FROM zap_predmety GROUP BY prednasajuci, cis_predm
--SELECT meno, priezvisko, nazov FROM zap_predmety JOIN ucitel ON (ucitel.os_cislo=zap_predmety.prednasajuci) JOIN predmet USING(cis_predm) GROUP BY meno, priezvisko, nazov
--SELECT meno, priezvisko FROM ucitel WHERE os_cislo IN(SELECT prednasajuci FROM zap_predmety WHERE os_cislo IN (SELECT os_cislo FROM student WHERE rocnik = 2 AND st_odbor < 200))
--SELECT meno, priezvisko, count(*) as pocet_predmetov FROM os_udaje JOIN student USING(rod_cislo) JOIN zap_predmety USING (os_cislo) WHERE skrok = 2008 GROUP BY
meno, priezvisko, skrok
--SELECT meno, priezvisko, count(*) as pocet_predmetov FROM student JOIN os_udaje USING(rod_cislo) JOIN zap_predmety USING (os_cislo) GROUP BY os_cislo, meno, priezvisko
--SELECT nazov FROM zap_predmety JOIN predmet USING(cis_predm) WHERE skrok = 2006 GROUP BY nazov, cis_predm HAVING count(*) >= 2

--SELECT meno, priezvisko, ROUND(AVG(DECODE(vysledok, 'A', 1, 'B', 1.5,'C',2,'D',2.5,'E',3,4)), 2) as priemer FROM student NATURAL JOIN os_udaje JOIN zap_predmety USING(os_cislo) GROUP BY meno, priezvisko, os_cislo
--SELECT meno, priezvisko, ROUND(AVG(DECODE(vysledok, 'A', 1, 'B', 1.5,'C',2,'D',2.5,'E',3,4)), 2) as priemer FROM student NATURAL JOIN os_udaje JOIN zap_predmety USING(os_cislo) GROUP BY meno, priezvisko, os_cislo HAVING AVG(DECODE(vysledok, 'A', 1, 'B', 1.5,'C',2,'D',2.5,'E',3,4)) < 3