A Database Error Occurred

Error Number: 1055

Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'freegames4rest.games_category.category' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

SELECT `game_id`, `category` FROM (`games_category`) WHERE `game_id` IN ('virtual_city_2_paradise_resort', 'stand_ofood_3', 'supermarket_mania_2', 'virtual_city', 'success_story') GROUP BY `game_id`