问题描述

关于mybatis多对多数据更新的问题

刚学mybatis，遇到如下的问题，纠结了很久啊。。。。。。各路神仙求帮忙
三个表：
drop table middles;
drop table students;
drop table courses;
create table students(
sid int(5) primary key,
sname varchar(10)
);
create table courses(
cid int(5) primary key,
cname varchar(10)
);
create table middles(
sid int(5),
cid int(5),
primary key(sid,cid)
);
学生实体和课程实体如下：
/**

• 学生(多方)
  /
  public class Student {
  private Integer id;
  private String name;
  private List courseList = new ArrayList();
  public Student(){}
  public Integer getId() {
  return id;
  }
  public void setId(Integer id) {
  this.id = id;
  }
  public String getName() {
  return name;
  }
  public void setName(String name) {
  this.name = name;
  }
  public List getCourseList() {
  return courseList;
  }
  public void setCourseList(List courseList) {
  this.courseList = courseList;
  }
  }
  /*
• 课程(多方)
• @author AdminTC
  */
  public class Course {
  private Integer id;
  private String name;
  private List studentList = new ArrayList();
  public Course(){}
  public Integer getId() {
  return id;
  }
  public void setId(Integer id) {
  this.id = id;
  }
  public String getName() {
  return name;
  }
  public void setName(String name) {
  this.name = name;
  }
  public List getStudentList() {
  return studentList;
  }
  public void setStudentList(List studentList) {
  this.studentList = studentList;
  }
  }
  现在的问题是，某个学生A在自己学的课程中，又加了一门课叫pentaKillCourse。
  代码流程如下：
  Course pentaKillCourse = new Course ();
  Student A = new Student（）；
  A.getCourseList().add(pentaKillCourse );
  studentService.update(user);
  --------------------------------studentService.update()方法如下-------------------------------------------
  public void update(User user) {
  userDao.updateUser(user);
  }
  --------------------------------userDao.updateUser()方法如下---------------------------------------------
  public void updateUser(User user) {
  SqlSession sqlSesion = sqlSessionFactory.openSession();
  sqlSesion.update("userNamespace.updateUser", user);

  }

  下面是userMapper：

  .........................................................................

解决方案

http://feiyeguohai.iteye.com/blog/1180898/