这是我的桌子：

DROP TABLE IF EXISTS `tbl_comments`;
CREATE TABLE IF NOT EXISTS `tbl_comments` (
  `id` int(11) NOT NULL auto_increment,
  `topic_id` int(11) NOT NULL,
  `user_id` int(11) NOT NULL,
  `text` text NOT NULL,
  `create_dt` datetime NOT NULL,
  `update_dt` timestamp NULL default CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  KEY `topic_id_2` (`topic_id`),
  KEY `user_id` (`user_id`),
  CONSTRAINT `tbl_comments_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `tbl_users` (`id`),
  CONSTRAINT `tbl_comments_ibfk_1` FOREIGN KEY (`topic_id`) REFERENCES `tbl_topics` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;


DROP TABLE IF EXISTS `tbl_users`;
CREATE TABLE IF NOT EXISTS `tbl_users` (
  `id` int(11) NOT NULL auto_increment,
  `username` varchar(20) NOT NULL default '',
  `password` varchar(128) NOT NULL default '',
  `email` varchar(128) NOT NULL default '',
  `activkey` varchar(128) NOT NULL default '',
  `superuser` int(1) NOT NULL default '0',
  `status` int(1) NOT NULL default '0',
  `create_at` timestamp NOT NULL default CURRENT_TIMESTAMP,
  `lastvisit_at` timestamp NOT NULL default '0000-00-00 00:00:00',
  PRIMARY KEY  (`id`),
  UNIQUE KEY `user_username` (`username`),
  UNIQUE KEY `user_email` (`email`)
) ENGINE=InnoDB AUTO_INCREMENT=14 DEFAULT CHARSET=utf8;


DROP TABLE IF EXISTS `tbl_topics`;
CREATE TABLE IF NOT EXISTS `tbl_topics` (
  `id` int(11) NOT NULL auto_increment,
  `group_id` int(11) NOT NULL,
  `user_id` int(11) NOT NULL,
  `header` varchar(255) NOT NULL,
  `text` text NOT NULL,
  `create_dt` datetime NOT NULL,
  `update_dt` timestamp NULL default CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`),
  KEY `user_id` (`user_id`),
  KEY `group_id` (`group_id`),
  CONSTRAINT `tbl_topics_ibfk_1` FOREIGN KEY (`group_id`) REFERENCES `tbl_groups` (`id`),
  CONSTRAINT `tbl_topics_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `tbl_users` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;

现在，当我尝试导入时出现错误：＃1005-无法创建表’kobeco_yii.tbl_comments’（错误号：150）（详细信息：Percona-
XtraDB，支持事务，行级锁定和外键）