今天遇到一个要删除外键列的问题,我发现:
show create table userfans;
| userfans | CREATE TABLE `userfans` ( `id` int(11) NOT NULL AUTO_INCREMENT, `status` int(11) DEFAULT NULL, `update_time` datetime DEFAULT NULL, `user` int(11) DEFAULT NULL, `fllower` int(11) DEFAULT NULL, `follower` int(11) DEFAULT NULL, PRIMARY KEY (`id`), KEY 'FKF025E60B81E8743E` (`fllower`), KEY `FKF025E60BAFF2360E` (`user`), KEY `FKF025E60BC1B86A61` (`follower`), CONSTRAINT `FKF025E60B81E8743E` FOREIGN KEY(`fllower`) REFERENCES `user` (`id`), CONSTRAINT `FKF025E60BAFF2360E` FOREIGN KEY (`user`) REFERENCES `user` (`id`), CONSTRAINT `FKF025E60BC1B86A61` FOREIGN KEY (`follower`) REFERENCES `user` (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 |
刚开始我想:是不是先删除KEY,再删除constraint,最后删除列?因为MySQL的外键列和Oracle不一样,MySQL的都是有KEY的;结果试了半天一直失败,最后发现,删除外键列竟然出奇的简单:
alter table userfans drop foreign key FKF025E60B81E8743E;
显示:
Query OK, 2 rows affected (0.32 sec) Records: 2 Duplicates: 0 Warnings: 0
真的是踏破铁鞋,白费功夫!