向自我引用父/子添加一对多关系 [英] Adding a one to many relationship to a self reference parent/child

问题描述

使用Spring和Hibernate，我可以在自引用类和另一个类中实现父/子之间的一对多关系。也就是说，这是自引用类：

DB：

  CREATE TABLE`employee`（
`employee_id` BIGINT（10）NOT NULL AUTO_INCREMENT，
`name` VARCHAR（50）NULL DEFAULT NULL，
`manager_id` BIGINT（20）NULL DEFAULT NULL，
 PRIMARY KEY（`employee_id`），
 CONSTRAINT`FK_MANAGER` FOREIGN KEY（`manager_id`）REFERENCES`employee` 
 $ b（`employee_id`））
  

型号：

  @Entity 
 @Table（name =employee）
 public class Employee {
 
 @Id 
 @Column（name =employee_id）
 @GeneratedValue 
 private Long employeeId; 
 
 @Column（name =name）
私有字符串名称; 
 
 @ManyToOne（cascade = {CascadeType.ALL}）
 @JoinColumn（name =manager_id）
私人员工经理; 
 
 @OneToMany（mappedBy =manager）
私人设置< Employee> employee = new HashSet< Employee>（）; 
  

现在我想为父/子（经理/员工）创建一对多关系）和另一个类如下：

  @OneToMany（mappedBy =manager）
 private List< Course> course = new ArrayList< Course>（）; 
 
 @OneToMany（mappedBy =lecturer）
 private List< Course> courses = new ArrayList< Course>（）; 
  

经理和员工都会与一门或多门课程相关联。课程课程：

  @Entity 
 @Table（name =courses）
 @Component 
 public class Courseizable实现Serializable 
 
 @ManyToOne 
 @JoinColumn（name =employee_id，insertable = false，updatable = false）
私人员工雇员; 
 
 @ManyToOne 
 @JoinColumn（name =manager_id，insertable = false，updatable = false）
私人员工经理; 
  

这是我想要实现的概述，但我想知道这是否可行如果是的话我该如何设置它在DB关系中，并且能够通过hibernate保存与db的关系。

解决方案

  @OneToMany（mappedBy =manager）
 private List< Course> managedCourses = new ArrayList< Course>（）; 
 
 @OneToMany（mappedBy =lecturer）
 private List< Course> lectuedCourses = new ArrayList< Course>（）; 
  

...

  @Entity 
 @Table（name =courses）
 @Component 
 public class Courseizable实现Serializable 
 
 @ManyToOne 
 @JoinColumn（name =lecturer_id，可插入= false，可更新= false）
私人员工讲师; 
 
 @ManyToOne 
 @JoinColumn（name =manager_id，insertable = false，updatable = false）
私人员工经理; 
  

Using Spring and Hibernate, can I implement a one to many relationship between the parent/child in a self reference class and another class. That is, this is the self reference class:

DB:

  CREATE TABLE `employee` (
  `employee_id` BIGINT(10) NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(50) NULL DEFAULT NULL,
  `manager_id` BIGINT(20) NULL DEFAULT NULL,
  PRIMARY KEY (`employee_id`),
  CONSTRAINT `FK_MANAGER` FOREIGN KEY (`manager_id`) REFERENCES `employee`    

  (`employee_id`))

Model:

  @Entity
  @Table(name="employee")
  public class Employee {

  @Id
  @Column(name="employee_id")
  @GeneratedValue
  private Long employeeId;

  @Column(name="name")
  private String name;

  @ManyToOne(cascade={CascadeType.ALL})
  @JoinColumn(name="manager_id")
  private Employee manager;

  @OneToMany(mappedBy="manager")
  private Set<Employee> employee = new HashSet<Employee>();

Now I want to create a one to many relationship for both of the parent/child (manager/employee) and another class like this:

  @OneToMany(mappedBy="manager")
  private List<Course> course = new ArrayList<Course>();

  @OneToMany(mappedBy="lecturer")
  private List<Course> courses = new ArrayList<Course>();

So both of manager and employee will have an association with one or many courses. The course class:

  @Entity
  @Table(name = "courses")
  @Component
  public class Course implements Serializable

  @ManyToOne
  @JoinColumn(name="employee_id", insertable=false, updatable=false)
  private Employee employee;

  @ManyToOne
  @JoinColumn(name="manager_id", insertable=false, updatable=false)
  private Employee manager;

That's the overview of what I'm trying to implement but I would like to know if this is possible and if so how would I set it up in a DB relationship and and be able to save the relationship to db via hibernate.

解决方案

@OneToMany(mappedBy="manager") 
private List<Course> managedCourses = new ArrayList<Course>();

@OneToMany(mappedBy="lecturer")
private List<Course> lectuedCourses = new ArrayList<Course>();

...

@Entity
@Table(name = "courses")
@Component
public class Course implements Serializable

@ManyToOne
@JoinColumn(name="lecturer_id", insertable=false, updatable=false)
private Employee lecturer;

@ManyToOne
@JoinColumn(name="manager_id", insertable=false, updatable=false)
private Employee manager;

这篇关于向自我引用父/子添加一对多关系的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！