-- 已有库升级：增加「支付4」一项（param=4）。可重复执行，已存在则不会插入。
INSERT INTO `site_pay_option` (`name`, `param`, `sort_order`, `enabled`)
SELECT '支付4', 4, 4, 1
FROM (SELECT 1 AS x) AS t
WHERE NOT EXISTS (SELECT 1 FROM `site_pay_option` WHERE `param` = 4 LIMIT 1);