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', 'aquascapes', 'fishdom3', 'fishdom_3', 'alexander_the_great_secrets_of_power', 'gardenscapes_2_mansion_makeover', 'royal_envoy_2', '4_elements_2', 'mystery_of_mortlake_mansion', 'farmscapes', 'fishdom_seasons_under_the_sea', 'fishdom_2', 'royal_envoy', 'fishdom_frosty_splash', 'gardenscapes', 'elementals_the_magic_key', 'fishdom_spooky_splash', 'fishdom_h2o_hidden_odyssey', 'call_of_atlantis') GROUP BY `game_id`