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 ('royal_envoy_ii', 'shadow_wolf_mysteries_bane_of_the_family', 'many_years_ago', 'ancient_rome_2', 'haunted_halls_revenge_of_doctor_blackmore_ce', 'awakening_the_skyward_castle', 'strangestone', 'fierce_tales_the_dogs_heart', 'dark_mysteries_the_soul_keeper', 'lake_house_children_of_silence_collectors_edition', 'fishdom3', 'halloween_the_pirates_curse', 'spooky_mahjong', 'mahjong_world_contest', 'age_of_enigma_the_secret_of_the_6th_ghost', 'mystery_trackers_black_isle', 'bricks_of_egypt_2_tears_of_the_pharaohs', 'joan_jade_and_the_gates_of_xibalba', 'ghost_encounters_deadwood', 'titanic_unsolved_mystery', 'mystery_series_a_vampire_tale') GROUP BY `game_id`