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 ('titanic_unsolved_mystery', 'lost_chronicles_salem', 'great_migration', 'explorer_contraband_mystery', 'nat_geo_adventure_ghost_fleet') GROUP BY `game_id`