Eroare a bazei de date

Error Number: 1055

Expression #8 of SELECT list is not in GROUP BY clause and contains nonaggregated column '' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

SELECT kc_photo_categories.*, COUNT( as num_photos, FROM kc_photo_categories LEFT JOIN kc_photos p ON p.parent_id = WHERE kc_photo_categories.visible = 1 AND p.visible = 1 GROUP BY (p.parent_id)