sum u okviru join tabela

upit je ovakav

SELECT nalozi.art_code, isporuka.kolicina, nalozi.sifra_koze, nalozi.dm_nalog, nalozi.nalog
FROM isporuka, nalozi
WHERE isporuka.isporuka = '1'
AND isporuka.dm_nalog = nalozi.dm_nalog


rezultat od prilike ovakav

400 1 CN072 670 704005
400 1 CN072 670 704005
180 1 AG111 696 704006

e sad, kako ja da napravim upit da za iste art_code sumiram kolicine?

Potpis

"The best code is no code at all."
- Zidar (ES član)
"Biggest obstacle to learning
SQL is unlearning procedural
programming." - Joe
Celko
"Minimize code, maximize data."
- A. Neil Pappalardo