JPA 中 one-toone 一對一 映射

使用者資訊表： User

 

@Entity @Table(name="users") @Cache(usage=CacheConcurrencyStrategy.READ_ONLY) public class User { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private Integer id; private String username; private String password;

 

使用者帳號表 Account

 

@Entity public class Account { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) private long id; private float money; @OneToOne(cascade=CascadeType.ALL) @JoinColumn(name="user_id") private User user;

 

 

@OneToOne(cascade=CascadeType.ALL)
@JoinColumn(name="user_id")
private User user;

 

注意 JoinColumn 指的是 account表中的外鍵的欄位名稱，  該註解只能用JoinColumn 而不能用Column

 

 

對應的資料庫(Hsqldb)中的表結構如下： 

drop table users if exists; create table users ( ID BIGINT GENERATED BY DEFAULT AS IDENTITY (start with 1), USERNAME VARCHAR(20) not null, PASSWORD VARCHAR(20) not null, AGE INT, BIRTHDAY TIMESTAMP, DESCRIB VARCHAR(20), PHOTO VARCHAR(20) ); alter table users add constraint users_pk primary key(id); drop table account if exists; create table account( ID BIGINT GENERATED BY DEFAULT AS IDENTITY (start with 1), user_id bigint not null, money float );