>[danger] 用于测试`远程一对多关联`的数据表 ``` CREATE TABLE `city` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `city_name` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) COMMENT='城市表'; CREATE TABLE `user` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT COMMENT '用户id', `city_id` int(11) DEFAULT NULL, `username` varchar(255) NOT NULL COMMENT '用户名', `nickname` varchar(255) DEFAULT NULL COMMENT '昵称', `password` char(32) DEFAULT NULL COMMENT '登陆密码', PRIMARY KEY (`id`) USING BTREE ) COMMENT='用户表'; CREATE TABLE `topic` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `user_id` int(11) DEFAULT NULL, `title` varchar(255) DEFAULT NULL, PRIMARY KEY (`id`) ) COMMENT='话题表'; ```