SQL hiba!

select distinct a.*, g.node gnode from fws__article a left join fws__art_grp g on (g.id=a.art_grp_no) left join fws__art_grp_key k on (k.art_id=a.id) where k.art_grp_no= and a.visible=1 and g.visible=1
You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'and a.visible=1 and g.visible=1' at line 1