JPA的ManyToOne

使用hibernate作为持久工具，一个部门下面有多个员工，要在新建部门时，同时将新增的员工一起插入表中。

mysql建表：

CREATE TABLE `department` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `dname` varchar(45) COLLATE utf8_bin DEFAULT NULL,
  PRIMARY KEY (`id`)
)

CREATE TABLE `employee` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `ename` varchar(45) COLLATE utf8_bin DEFAULT NULL,
  `phone` varchar(45) COLLATE utf8_bin DEFAULT NULL,
  PRIMARY KEY (`id`)
)

/**
 * 部门：与员工一对多关系
 *
 */
@Entity
@Table(name="department")
public class Department {
    
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id; 
    
    @Column(length=20)
    private String dname; //部门名称
    
    @OneToMany
    private List<Employee> employeeList = new ArrayList<>(); //员工集合

    // get/set方法

/**
 * 员工：与部门多对一关系
 *
 */
@Entity
@Table(name="employee")
public class Employee {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id; //ID
    
    @Column(length=20)
    private String ename; //员工姓名
    
    @Column(length=20)
    private String phone; //电话
    
    @ManyToOne
    private Department department; //所属部门
   
    //get/set方法
}

//使用
Department d = new Department();
d.setDname("soft");

Employee e1 = new Employee();
e1.setEName("liao");
e1.setPhone("110")
Employee e2 = new Employee();
e2.setEName("liao");
e2.setPhone("110")

List<Employee> list = new ArrayList<>();
list.add(e1);
list.add(e2);
d.setEmployeeList(list);

当插入部门时，就能自动插入相应的级联数据