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 ('bejeweled_3', 'amazing_adventures_the_riddle_of_two_knights', 'mystery_pi_curious_case_counterfeit_cove', 'amazing_adventures_the_forgotten_dynasty', 'banana_bugs', 'mystery_pi_the_london_caper', 'zumas_revenge_adventure', 'plants_vs_zombies', 'escape_rosecliff_island', 'the_wizards_pen', 'mystery_p_i_the_vegas_heist', 'amazing_adventures_the_lost_tomb', 'peggle_deluxe', 'zuma') GROUP BY `game_id`