JPA -如何在子表中引用属于复合键的列
如何从复合字段映射其中一列？
我有两个表:问题和Question_options。
CREATE TABLE `question` (
`question_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
`question` varchar(500) NOT NULL,
PRIMARY KEY (`question_id`)
) ENGINE=InnoDB AUTO_INCREMENT=501 DEFAULT CHARSET=utf8;
CREATE TABLE `question_options` (
`question_id` smallint(5) unsigned NOT NULL,
`option_id` varchar(3) NOT NULL,
`option_description` varchar(500) NOT NULL,
PRIMARY KEY (`question_id`, `option_id`),
KEY `idx_fk_op_question_id` (`question_id`),
KEY `idx_fk_op_option_id` (`option_id`),
CONSTRAINT `fk_op_question_id` FOREIGN KEY (`question_id`) REFERENCES `question` (`question_id`) ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;在Question.java中：
@JoinColumn(name = "question_id", nullable = false)
private List<QuestionOption> questionOptions;在QuestionOption.java中
@EmbeddedId
private QuestionOptionPK id;在QuestionOptionPK.java中
@Column(name="question_id", insertable=true, updatable=false, unique=true, nullable=false)
private long questionId;
@Column(name="option_id", insertable=true, updatable=false, unique=true, nullable=false, length=3)
private String optionId;在Question.java中，我指的是复合键(QuestionOptionPK)的一个字段是questionId。
但我得到的错误如下：
严重: web应用程序中的Servlet mvc-dispatcher抛出load()异常org.hibernate.MappingException:实体映射中的重复列: com.mobily.model.QuestionOption列: question_id (应映射为insert="false“update="false")
回答 2
Stack Overflow用户
发布于 2015-12-10 23:21:43
您需要使用派生身份。
Question.java：
@Entity
public class Question {
@Id
@Column(name="question_id")
private long id;
@OneToMany(mappedBy="question")
private List<QuestionOption> questionOptions;
...
}QuestionOption.java：
@Entity
@Table(name="question_options")
public class Question {
@EmbeddedId
private QuestionOptionPK id;
@ManyToOne
@JoinColumn(name = "question_id")
@MapsId("questionId") // maps questionId attribute of the embedded ID
private Question question;
...
}QuestionOptionPK.java：
@Embeddable
public class QuestionOptionPK {
private long questionId; // corresponds to the PK type of Question
@Column(name="option_id")
private String optionId;
}派生身份在JPA 2.1规范的2.4.1节中进行了讨论。
Stack Overflow用户
发布于 2015-12-14 15:39:42
我改变了我的桌子结构。我删除了复合主键，而不是使用option_id作为主键，现在option_id是一个数字。我下定决心了。
CREATE TABLE `question` (
`question_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
-- `category` varchar(25) NOT NULL,
`question` varchar(500) NOT NULL,
-- `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`question_id`)
-- KEY `idx_fk_category` (`category`)
) ENGINE=InnoDB AUTO_INCREMENT=501 DEFAULT CHARSET=utf8;
CREATE TABLE `question_options` (
`option_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT,
`question_id` smallint(5) unsigned NOT NULL,
`option_key` varchar(3) NOT NULL, -- It is like a, b, c... .
`option_description` varchar(500) NOT NULL,
-- `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`option_id`),
KEY `idx_fk_op_question_id` (`question_id`),
-- KEY `idx_fk_op_option_id` (`option_id`),
CONSTRAINT `fk_op_question_id` FOREIGN KEY (`question_id`) REFERENCES `question` (`question_id`) ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=601 DEFAULT CHARSET=utf8;https://stackoverflow.com/questions/34203888
复制相似问题
腾讯云开发者
Copyright © 2013 - 2026 Tencent Cloud. All Rights Reserved. 腾讯云 版权所有
深圳市腾讯计算机系统有限公司 ICP备案/许可证号：粤B2-20090059 
粤公网安备44030502008569号
腾讯云计算（北京）有限责任公司 京ICP证150476号 | 京ICP备11018762号