//Vypise nazvy alb, ktera jsou na CD evidovana vice nez 2 krat
select Nazev_A as Album from CD natural join Album group by Nazev_A having Count(Nazev_A)>2;
//Vypise kolik CD obchod eviduje
select Count(*) as Pocet_CD from CD;
//Vypise vsechny zakazniky, kteri si jiz neco objednali
select distinct RC_Zak as Rodne_Cislo,Jmeno_Zak as Jmeno,Adresa,Telefon from Zakaznik  natural join Objednavka;
//Vypise vsechny faktury se jmeny a RC zakazniku, ktere jiz byly zaplaceny
select Cis_F as Cislo_faktury,dat_vystav as Vystaveno, RC_Zak as RC_Zakaznika, Jmeno_Zak as Jmeno from Faktura natural join za natural join objednavka natural join Zakaznik where Vyrizena='A'; 
//Vypise nazvy alb a pocet pisnicek, ktere obsahuji
select Nazev_A as Album,Count(Nazev_P) as Pocet_pisnicek from Album natural join Obsazena group by Nazev_A;
//Vypis vsechny zakazniky, kteri jeste nezaplatili za nejakou fakturu
select distinct RC_Zak as Rodne_Cislo,Jmeno_Zak as Jmeno from Faktura natural join za natural join objednavka natural join Zakaznik where Vyrizena='N'; 
//Vypise prumernou cenu alba
select AVG(Cena) as Prumerna_cena_Alba from Album;
//Vypise vsechny zamestnance, kteri vystavili alespon jednu fakturu
select distinct ID_Zam as ID_Zamestnance, Jmeno_Zam as Jmeno_Zamestnance from Zamestnanec natural join Faktura;
//Vypise vsechny zakazniky a ceny vsech jejich objednavek
select RC_Zak,Jmeno_Zak, Sum(Pocet*Cena) from Zakaznik natural join Objednavka natural join Album group by RC_Zak,Jmeno_Zak;
//Vypis vsechny interprety, kteri nazpivali alespon dve pisne.
select I.ID_I as ID_Interpreta,Jmeno_I as Jmeno from Interpret I join Pisen P on(I.ID_I=P.ID_I) group by I.ID_I,Jmeno_I having Count(Nazev_P)>=2;