Question

我尝试恢复使用mysqldump创建的转储。在恢复相同的时候，我得到了这个

第63行的错误1215（HY000）：无法添加外键约束

DROP TABLE IF EXISTS `channel_tags`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `channel_tags` (
  `channel_tag_id` bigint(20) NOT NULL AUTO_INCREMENT,
  `channel_id` bigint(20) NOT NULL,
  `tag_name` varchar(60) NOT NULL,
  PRIMARY KEY (`channel_tag_id`),
  KEY `channel_id_idx` (`channel_id`),
  KEY `tag_name_idx` (`tag_name`),
  CONSTRAINT `ct_channel_fk` FOREIGN KEY (`channel_id`) REFERENCES `channel_shard` (`channel_id`),
  CONSTRAINT `ct_tag_fk` FOREIGN KEY (`tag_name`) REFERENCES `tags` (`tag_name`)
) ENGINE=InnoDB AUTO_INCREMENT=833 DEFAULT CHARSET=utf8mb4;
/*!40101 SET character_set_client = @saved_cs_client */;

DROP TABLE IF EXISTS `tags`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `tags` (
  `tag_name` varchar(60) NOT NULL,
  `created_at` datetime DEFAULT NULL,
  `updated_at` datetime DEFAULT NULL,
  PRIMARY KEY (`tag_name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
/*!40101 SET character_set_client = @saved_cs_client */;

create table语句的顺序是相同的。

SHOW ENGINE INNODB状态\ G给了我这个：

------------------------
LATEST FOREIGN KEY ERROR
------------------------
2015-12-07 17:20:16 1ac30b000 Error in foreign key constraint of table sde/channel_tags:
 FOREIGN KEY (`tag_name`) REFERENCES `tags` (`tag_name`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8mb4:
Cannot find an index in the referenced table where the
referenced columns appear as the first columns, or column types
in the table and the referenced table do not match for constraint.
Note that the internal storage type of ENUM and SET changed in
tables created with >= InnoDB-4.1.12, and such columns in old tables
cannot be referenced by such columns in new tables.
See http://dev.mysql.com/doc/refman/5.6/en/innodb-foreign-key-constraints.html
for correct foreign key definition.

有人能让我知道这里发生了什么吗？

Answer 1

我也遇到了这个错误。

我猜你做的和我一样：将整个数据库设置为UTF8，然后将一些列/表更改为UTF8MB4。

我不知道如何解决它。但是，有一种解决方法：将所有UTF8MB4更改回转储SQL文件中的UTF8，将其还原到数据库中，并通过以下命令手动将特定列更改为UTF8MB4：

ALTER DATABASE [dbname] CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;

ALTER TABLE [tablename] CHANGE [colname] [colname] VARCHAR(191) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin;

SET FOREIGN_KEY_CHECKS=0;

ALTER TABLE [tablename] CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

SET FOREIGN_KEY_CHECKS=1;

Answer 2

我的转储和数据库中没有utf8mb4字符集，但是出现了问题。

我解决了它删除所有表并在之后恢复我的转储的情况。

使用以下内容：How to remove all MySQL tables from the command-line without DROP database permissions?

Mysql转储还原失败：无法添加外键约束

2 个答案: