Hibernate多对多单向关联(Annotation配置)

package edu.xaut.hibernate;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;

@Entity
public class Teacher {
    private int id;
    private String name;
    private Set<Student> students = new HashSet<Student>();

    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    @Column(length = 20)
    public String getName() {
        return name;
    }

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

    @ManyToMany
    @JoinTable(name = "tea_stu",
            joinColumns = { @JoinColumn(name = "teacher_id", referencedColumnName = "id") },
            inverseJoinColumns = { @JoinColumn(name = "student_id", referencedColumnName = "id") }
            )
    public Set<Student> getStudents() {
        return students;
    }

    public void setUsers(Set<Student> students) {
        this.students = students;
    }
}

package edu.xaut.hibernate;

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

@Entity
public class Student {
    private int id;
    private String name;
    private String title;

    @Id
    @GeneratedValue
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    @Column(length = 20)
    public String getName() {
        return name;
    }

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

    @Column(length = 10)
    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }   
}

生成的SQL语句如下：
create table Student (
        id integer not null auto_increment,
        name varchar(20),
        title varchar(10),
        primary key (id)
    )

    create table Teacher (
        id integer not null auto_increment,
        name varchar(20),
        primary key (id)
    )

    create table tea_stu (
        teacher_id integer not null,
        student_id integer not null,
        primary key (teacher_id, student_id)
    )

    alter table tea_stu
        add index FKAA30258570F338D0 (teacher_id),
        add constraint FKAA30258570F338D0
        foreign key (teacher_id)
        references Teacher (id)

    alter table tea_stu
        add index FKAA3025856057EE30 (student_id),
        add constraint FKAA3025856057EE30
        foreign key (student_id)
        references Student (id)