刪除重復行，并保留id最大的：
DELETE a
FROM user1_test a JOIN
(SELECT user_name, COUNT(*), MAX(id) AS id FROM user1_test GROUP BY user_name HAVING COUNT(*)>1) b
ON a.user_name = b.user_name
WHERE a.id < b.id;
SELECT user_name, 'arms' AS equipment, arms FROM user1 a JOIN user1_equipment b ON a.id = b.user_id
UNION ALL
SELECT user_name, 'clothing' AS equipment, arms FROM user1 a JOIN user1_equipment b ON ...
UNION ALL
SELECT user_name, 'shoe' AS equipment, arms FROM user1 a JOIN user1_equipment b ON ...
CREATE TABLE user1_equipment (
id TINYINT UNSIGNED AUTO_INCREMENT NOT NULL,
user_id SMALLINT UNSIGNED,
arms VARCHAR(10) CHARACTER SET utf8 DEFAULT NULL,
clothing VARCHAR(10) CHARACTER SET utf8 DEFAULT NULL,
shoe VARCHAR(10) CHARACTER SET utf8 DEFAULT NULL,
PRIMARY KEY(id)
);
