mysql - 如何使用 Entity Framework 1 和 MySQL 更新多对多相关对象？

Question

我有这样的问题。我将 EF1 与 VS2008 SP1 和 MySQL 与 MySQL Connector/Net 6.3.4 一起使用

我的数据库架构如下所示:

CREATE TABLE IF NOT EXISTS `credential` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=3 ;

CREATE TABLE IF NOT EXISTS `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=3 ;

CREATE TABLE IF NOT EXISTS `user_credential` (
  `user_id` int(11) NOT NULL,
  `credential_id` int(11) NOT NULL,
  KEY `credential_id` (`credential_id`),
  KEY `user_id` (`user_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

ALTER TABLE `user_credential`
  ADD CONSTRAINT `user_credential_ibfk_2` FOREIGN KEY (`credential_id`) REFERENCES    `credential` (`id`) ON DELETE CASCADE,
  ADD CONSTRAINT `user_credential_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE CASCADE;

当我尝试执行以下代码时，我遇到了无法理解的异常

var entities = new studyEntities();

var user = new User { Name = "test" };
var credential = new Credential { Name = "admin" };

entities.AddToCredentialSet(credential);
entities.AddToUserSet(user);

entities.SaveChanges();
user.Credentials.Add(credential);
entities.SaveChanges(); // He I have a strange exception thrown


You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '(SELECT
  `user_credential`.`credential_id`, 
  `user_credential`.`user_' at line 1

这是什么意思？我怎样才能看到整个查询来寻找其中的问题？或者我做错了什么？

Answer 1

我有同样的错误，因为我在中间表中没有主键。

这为我解决了问题:

CREATE TABLE IF NOT EXISTS `user_credential` (
  `user_id` int(11) NOT NULL,
  `credential_id` int(11) NOT NULL,

  PRIMARY KEY(`user_id`, `credential_id`)
  KEY `user_id` (`user_id`)

  CONSTRAINT .... FOREIGN KEY....
  CONSTRAINT .... FOREIGN KEY....

) ENGINE=InnoDB DEFAULT CHARSET=utf8;