@JoinColumn name=cid是什么意思?
慕娘9557946
2017-09-13 15:44
//一对多 双向关联
Student.java:
@ManyToOne(cascade = {CascadeType.ALL},fetch = FetchType.EAGER)
@JoinColumn(name = "cid") /// ????
private ClassRoom classRoom;
ClassRoom.java
@Id
@GeneratedValue(generator = "cid")
@GenericGenerator(name = "cid",strategy = "assigned")
@Column(length = 4)
private String cid;
private String cname;
@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
@JoinColumn(name = "cid") /// ???
private Set<Student> stus;请问cid指的是什么 ??? 这个cid指的是 生成的外键字段的名词 吗?
有没有要求必须要与主键cid属性同名?如果没有要求的换个其他比较好, 都叫cid这样会有歧义.
还有双向关联双方实体类 @JoinColumn name="xxx" 是都需要写一样吗?
2回答
-
- MartinCode
- 2018-02-24 16:07:24
@JoinColumn(name="rid", referencedColumnName="cid") //name=定义外键在本表的字段名 referencedColumnName =关联外键对象的哪个字段
-
- 慕娘9557946
- 2017-09-13 15:48:29
提问居然乱码了
ClassRoom :
@Id
@GeneratedValue(generator = "cid")
@GenericGenerator(name = "cid",strategy = "assigned")
@Column(length = 4)
private String cid;
private String cname;
@OneToMany(cascade = CascadeType.ALL,fetch = FetchType.LAZY)
@JoinColumn(name = "cid")
private Set<Student> stus;Student :
@Id
@GeneratedValue
private int sid;
@Column(length = 25)
private String sname;
private String gender;
private Date birthday;
private String major;
@ManyToOne(cascade = {CascadeType.ALL},fetch = FetchType.EAGER)
@JoinColumn(name = "cid")
private ClassRoom classRoom;
Hibernate注解
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