使用@JoinTable 的 Hibernate 一对多映射问题
[英]Hibernate One-To-Many Mapping issue using @JoinTable
问题描述
I have two tables: User And Team
我有两个表：用户和团队
User用户
- UserId用户身份
- 4 digit Password/pin 4 位密码/pin
Team团队
- Team_id Team_id
- TeamName队名
Constraints 1 user can only belong to one team whereas 1 team can have many users.约束1 个用户只能属于一个团队，而 1 个团队可以有多个用户。 I have already normalized the database and the third table()Join Table) named user_team will be as follows:我已经对数据库进行了规范化，名为 user_team 的第三个 table()Join Table) 将如下所示：
User_Team[JOIN TABLE] User_Team[加入表]
- User_id(This is a Foreign Key from User Table) User_id（这是来自用户表的外键）
- Team_Id(This is a Foreign Key from Team Table) Team_Id（这是团队表中的外键）
While implementing this in Hibernate using @JoinColumn Attribute and @OneToMany annotations its throwing following error:在 Hibernate 中使用 @JoinColumn Attribute 和 @OneToMany 注释实现这一点时，它抛出以下错误：
A Foreign key refering com.project.hibernate.Team from com.project.hibernate.User has the wrong number of column.
Exception in thread "main" org.hibernate.AnnotationException: A Foreign key refering com.project.hibernate.Team from com.project.hibernate.User has the wrong number of column.
1 个解决方案
解决方案1
1 已采纳 2019-02-20 15:33:46
You have a composed key containing two fields:您有一个包含两个字段的组合键：
@Id
@Column(name="team_id")
private String team_id;
@Id
@Column(name="team_name")
private String team_name;
Whereas your join table has only one key per table:而您的连接表每个表只有一个键：
@OneToMany(cascade=CascadeType.ALL)
@JoinTable(name="user_team",
joinColumns=@JoinColumn(name="team_id"),
inverseJoinColumns=@JoinColumn(name="user_id"))
private List<User> user;
You need to use all keys that make the relationship, something like that (of course table also need to have the right columns):您需要使用所有建立关系的键，类似的东西（当然表也需要有正确的列）：
@OneToMany(cascade=CascadeType.ALL)
@JoinTable(name="user_team",
joinColumns=@JoinColumn({@JoinColumn(name="team_id"), @JoinColumn(name="team_name")}),
inverseJoinColumns=@JoinColumn(name="user_id"))
private List<User> user;
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