Hibernate Annotations 关联

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Hibernate

Hibernate

如果People1定义了mappedBy，则在work表生成到People1的外键，work是这个关系的拥有者；
如果work定义了mappedBy，则在People1表生成到work的外键，People1是这个关系的拥有者。

在双向关联中，有且仅有一段是作为主体（owner）端在的：
主体端负责维护联接（即更新），对于不需要维护这种关系得从表则通过mappedBy进行声明。

OneToOne

There are three cases for one-to-one associations:

1. either the associated entities share the same primary keys values,

2. a foreign key is held by one of the entities (note that this FK column in the database should be constrained unique to simulate one-to-one multiplicity),

3. a association table is used to store the link between the 2 entities (a unique constraint has to be defined on each fk to ensure the one to one multiplicity)

the first:share the same primary keys values

@Entity
public class People1 implements java.io.Serializable {
private Integer id;
private String name;
private Work work;
@Id
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@OneToOne(cascade = CascadeType.ALL)
@PrimaryKeyJoinColumn
public Work getWork() {
return work;
}
public void setWork(Work work) {
this.work = work;
}
@Entity
public class Work implements java.io.Serializable {
private int id;
private String corpname;
private People1 people1;
@OneToOne(mappedBy = "work")
public People1 getPeople1() {
return this.people1;
}
public void setPeople1(People1 people1) {
this.people1 = people1;
}
public String getCorpname() {
return corpname;
}
public void setCorpname(String corpname) {
this.corpname = corpname;
}
@Id
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}

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第一个Spring程序 | 第一个Hibernate with Annotation程式(转 ...

2007-06-03 23:51
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1 楼 xiangzhengyan 2007-06-04

双向 onetomany manytoone 有疑问

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