Show the id of the game platform with the most sales in region 2.
id of the game platform refers to game_platform_id; the most sales refers to max(num_sales); region 2 refers to region_id = '2'
SELECT T1.game_platform_id FROM ( SELECT T.game_platform_id, SUM(T.num_sales) FROM region_sales AS T WHERE T.region_id = 2 GROUP BY T.game_platform_id ORDER BY SUM(T.num_sales) DESC LIMIT 1 ) T1
database name:db_id video_games
genre table genre Cols: id dtype integer, genre_name dtype text, 
game table game Cols: id dtype integer, genre id dtype integer, game name dtype text, 
platform table platform Cols: id dtype integer, platform_name dtype text, 
publisher table publisher Cols: id dtype integer, publisher_name dtype text, 
game_publisher table game_publisher Cols: id dtype integer, game id dtype integer, publisher id dtype integer, 
game_platform table game_platform Cols: id dtype integer, game publisher id dtype integer, platform id dtype integer, release year dtype integer, 
region table region Cols: id dtype integer, region_name dtype text, 
region_sales table region_sales Cols: region_id dtype integer, game platform id dtype integer, number sales dtype real, 
