Ako sam te dobro razumeo, hoćeš ovo?
SELECT title_grart,
GROUP_CONCAT(title_art ORDER BY title_art SEPARATOR ", ") AS artikli
FROM tbl_artikli
INNER JOIN tbl_grupa_art ON idgrart_art = idgr_art
WHERE idtop_grart =
1
GROUP BY idgr_art
"Common sense is not so common." - Voltaire