一 ?: 一對一

1 一對一主鍵關聯

Customer.java

import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne; import javax.persistence.PrimaryKeyJoinColumn;/*** 一對一主鍵關聯* **/ @Entity public class Customer {@Idprivate int id;private String name;@OneToOne@PrimaryKeyJoinColumnprivate CustomerNo customerNo;}
CustomerNo.java

import javax.persistence.CascadeType; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne;/*** 一對一主鍵關聯* **/ @Entity public class CustomerNo {@Idprivate int id;private String sn;@OneToOne(mappedBy = "customerNo")private Customer customer; }
最后表結構

2 一對一外鍵關聯

Customer1.java

import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.JoinColumn; import javax.persistence.OneToOne; import javax.persistence.PrimaryKeyJoinColumn;/*** 一對一外鍵關聯* **/ @Entity public class Customer1 {@Idprivate int id;private String name;@OneToOne@JoinColumn(name="customerNoId",unique=true)private CustomerNo1 customerNo1;}
CustomerNo1.java

import javax.persistence.CascadeType; import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToOne;/*** 一對一外鍵關聯* **/ @Entity public class CustomerNo1 {@Idprivate int id;private String sn;@OneToOne(mappedBy = "customerNo1")private Customer1 customer1; }
最后表結構

二 一對多

1?一對多單向關聯

Classes.java

import java.util.Set;import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany;/*** 一對多單向關聯* */ @Entity public class Classes {@Idprivate int id;private String name;@OneToManyprivate Set<Student> students; }
Student.java

package learning.oneToMany import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id;/*** 一對多單向關聯* */ @Entity public class Student {@Id@GeneratedValueprivate int id;private String name; }
最后表結構

2?一對多雙向關聯

Classes1.java

import java.util.Set;import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.OneToMany;/*** 一對多雙向關聯* */ @Entity public class Classes1 {@Idprivate int id;private String name;@OneToMany(mappedBy="classes1")private Set<Student1> students1; }
Student1.java

package learning.oneToMany import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.ManyToOne; /*** 一對多雙向關聯* */ @Entity public class Student1 {@Id@GeneratedValueprivate int id;private String name;@ManyToOneprivate Classes1 classes1; }
最后表結構

三 多對多

Role.java

import java.util.Set;import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.JoinTable; import javax.persistence.ManyToMany;/*** 多對多關聯映射* */ @Entity public class Role {@Idprivate int id;private String name;@ManyToMany@JoinTable(name="T_Role_Staff") //中間表private Set<Staff> staffs; }
Staff.java

import java.util.Set;import javax.persistence.Entity; import javax.persistence.Id; import javax.persistence.ManyToMany;/*** 多對多關聯映射* */ @Entity public class Staff {@Idprivate int id;private String name;@ManyToMany(mappedBy="staffs")private Set<Role> roles; }

最后表結構

總結

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