mysql合服 更新相同的用户名前追加服务器编号

表结构:

CREATE TABLE IF NOT EXISTS `user` (
  `user_id` int(11) NOT NULL COMMENT '主键',
  `user_level` int(11) NOT NULL DEFAULT 0 COMMENT '等级',
  `user_name` varchar(32) NOT NULL DEFAULT 0 COMMENT '名称',
  `server_id` int(11) NOT NULL DEFAULT 0 COMMIT '服务器编号',
  PRIMARY KEY (`user_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

示例sql：

UPDATE user a,
          (
            SELECT a.user_id FROM user a,(SELECT user_name,count(user_id) as num FROM user GROUP BY user_name HAVING num > 1) b WHERE a.user_name = b.user_name 
           ) b
SET a.user_name = concat('s', server_id, '.', user_name) 
WHERE a.user_id = b.user_id