使用@GeneratedValue（strategy = GenerationType.AUTO）时，Hibernate不保存对象

Question

I am learning Hibernate with MySql data base, while making small project i come up with strange behave of hibernate. I am trying to save one entity (code is below), but entity not getting persist into DB. i am using session.save(e) method only. It is working if i am using @GeneratedValue(strategy=GenerationType.IDENTITY) and not if i am using @GeneratedValue(strategy=GenerationType.AUTO) .

Again if i use session transaction ( begin and commit ) it is working in both case (AUTO and IDENTITY).

Again if i use two different entity one with AUTO and another with IDENTITY it is working.

First Entity

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

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

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "EMP_ID")
    private int empId;

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

    public int getEmpId() {
        return empId;
    }

    public void setEmpId(int empId) {
        this.empId = empId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

Second Entity

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "SUPEMPLOYEE")
public class SupperEmploye {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "EMP_ID")
    private int empId;

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

    public int getEmpId() {
        return empId;
    }

    public void setEmpId(int empId) {
        this.empId = empId;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

}

Code for save entity

Session s= HibernateConfig.getSessionFactory().openSession();
        //s.getTransaction().begin(); //working if add

        Employee e= new Employee();
        e.setName("Employee");
        s.save(e);

        SupperEmploye se = new SupperEmploye();
        se.setName("Super Employee");
        s.save(se);

        s.close();
        //s.getTransaction().commit(); // Working if add
        HibernateConfig.getSessionFactory().close();

NOTE: Using hibernate 5, MySQL 8, JAVA 8

please comment if need more info

Answer 1

尝试这个

@GeneratedValue(strategy=GenerationType.IDENTITY)

Answer 2

You should use

@GeneratedValue(strategy = GenerationType.AUTO, generator = "native") 

instead of

@GeneratedValue(strategy = GenerationType.AUTO)

Read below this nice article on this.

https://vladmihalcea.com/why-should-not-use-the-auto-jpa-generationtype-with-mysql-and-hibernate/