单项主键关联指的是:husband和wife之间有关联关联的。但是是用主键做关联的,说白了就是husband的id会参考wife的id(husband的id是1,n那么它所对应的wife的id也是1)。
Husband.java:
wife.java:
生成的建表语句:
create table Husband (
id integer not null auto_increment,
name varchar(255),
primary key (id)
)
create table Wife (
id integer not null auto_increment,
name varchar(255),
primary key (id)
)
alter table Husband
add index FKAEEA401BF5211E1C (id),
add constraint FKAEEA401BF5211E1C
foreign key (id)
references Wife (id)
schema export complete
可以看见Wife和Husband表里面没有外键的字段,但是两个主键之间会设关联。
(看数据库的图形化界面,你也会看到husband的id字段上有小钥匙的图标,这就是一个主键关联)
Husband.java:
package cn.edu.hpu.one2one;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.PrimaryKeyJoinColumn;
@Entity
public class Husband {
private int id;
private String name;
private Wife wife;
@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@OneToOne
//@JoinColumn(name="wifeid")
@PrimaryKeyJoinColumn //用主键做连接的一种东西
public Wife getWife() {
return wife;
}
public void setWife(Wife wife) {
this.wife = wife;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
wife.java:
package cn.edu.hpu.one2one;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
@Entity
public class Wife {
private int id;
private String name;
private Husband husband;
@Id
@GeneratedValue
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
@OneToOne(mappedBy="wife")
public Husband getHusband() {
return husband;
}
public void setHusband(Husband husband) {
this.husband = husband;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
生成的建表语句:
create table Husband (
id integer not null auto_increment,
name varchar(255),
primary key (id)
)
create table Wife (
id integer not null auto_increment,
name varchar(255),
primary key (id)
)
alter table Husband
add index FKAEEA401BF5211E1C (id),
add constraint FKAEEA401BF5211E1C
foreign key (id)
references Wife (id)
schema export complete
可以看见Wife和Husband表里面没有外键的字段,但是两个主键之间会设关联。
(看数据库的图形化界面,你也会看到husband的id字段上有小钥匙的图标,这就是一个主键关联)