英文:
In @OneToMany making One's side owner
问题
假设有一个名为 Employee 的类，其中有一个关联集合 Course。
class Employee {
@OneToMany
private Set<Course> courses;
}
我想要类似下面的结果：
first_name | last_name | course_ids
Jill | Smith. | 1,2,3
Eve | Jackson. | 1,4,5
我在 Hibernate 方面了解不是很深，可以有人帮忙吗？
英文:
Let's say there is an Employee's which has a collection of Course.
class Employee {
@OneToMany
private Set<Course> courses.
}
I want something like below
first_name | last_name | course_ids
Jill | Smith. | 1,2,3
Eve | Jackson. | 1,4,5
I am not so advanced in hibernate, can someone please help.
答案1
得分: 0
以下是翻译好的内容：
我即将向您展示的方法是一对多单向方法。在您的数据库中，您应该为课程创建一张表，其中必须包含employee_id作为外键和课程id作为主键。然后，按照以下方式创建Course类（假设数据库中的课程表名为“course”）：
@Entity
@Table(name = "course")
public class Course {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name ='id')
private int id;
//您可以根据课程表添加其他字段
//添加一个无参数的构造函数，以及getter和setter方法
}
请注意，employee_id 不在 Course 类中。然后创建 Employee 类：
@Entity
@Table(name ="employee")
public class Employee {
//ID 和其他字段
@OneToMany
@JoinColumn(name="course_id")
private List<Course> courses;
//构造函数、getter 和 setter 方法等
}
您必须在您创建的每个实体中定义 getter 和 setter 方法，因为 Hibernate 使用它们将从数据库检索到的值设置到实体的字段中。
英文:
The method that I am about to show to you is the One to many unidirectional method.
In your database you should create a table for courses and it must contain employee_id as a foreign key and an id of the course as a primary key.
Then, create the Course class as below.(let's assume that the name of the course table in the database is "course":
@Entity
@Table(name = "course")
public class Course {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name ='id')
private int id;
//You can add another fields based on your course table
//add a constructor with no arguments, getters and setters
}
Notice that the employee_id is not in the course class.Then create the employee class:
@Entity
@Table(name ="employee")
public class Employee {
//ID and other fields
@OneToMany
@JoinColumn(name="course_id")
private List<Course> courses;
//Constructor,getters and setters,...
}
You must define getters and setters in every Entity you create because Hibernate uses them to set the fields in the Entity with the value retrieved from the database
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