It's kind hard to explain, but I'm looking for replace this with IF EXISTS to improve performance:
Select ... ,
IF((SELECT COUNT( t.tab_id ) FROM tabs t WHERE t.marker_id = m.marker_id)>0,1,0) multimedia, ....
FROM markers m
WHERE ....
On this query, I would like to have a temporary column called "multimedia" filled by 1 if theres multimedia or 0 if there's not.
This code is executed by PHP...