MyBatis多表操作的实现

public class Student {
  private Integer id;
  private String name;
  private Boolean age;
  private String sex;
  private StudentStatus studentStatus;

  // set and get
}

public class StudentStatus {
  private Integer id;
  private String num;
  private String major;

  // set and get
}

public class StudentStatus {
  private Integer id;
  private String num;
  private String major;

  // set and get
}

	
	
	


	select user_id, user_name, hashed_password from some_table where id = #{id}

<&＃63;xml version="1.0" encoding="UTF-8" &＃63;>


  
    
    
    
  
  
    select * from student s, student_status st where s.st_id = st.st_id
  

  
    
    
    
    
    
      
      
      
    
  
  
    select * from student s, student_status st where s.st_id = st.st_id
  

<&＃63;xml version="1.0" encoding="UTF-8" &＃63;>


  
    
  
  
  
    select * from student s, student_status st where s.st_id = st.st_id
  

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/3
 * @description 测试类
 */
public class MybatisDemo {

  @Test
  public void TestA() throws IOException {
    // 加载核心配置文件
    InputStream resourceAsStream = Resources.getResourceAsStream("mybatis.xml");
    // 获得 sqlSession 工厂对象
    SqlSessionFactory sqlSessiOnFactory= new SqlSessionFactoryBuilder().build(resourceAsStream);
    // 获得 sqlSession 对象
    SqlSession sqlSession = sqlSessionFactory.openSession();

    List list = sqlSession.selectList("com.software.mybatis.dao.StudentDao.findAll");

    System.out.println(list);
  }
}

public class Student {
  private Integer sId;
  private String sName;
  private Long sAge;
  private String sSex;
  private Integer cId;
	
	// set and get
}

public class Class {
  private Integer cId;
  private String cName;
  private String cAddr;
  private List students;
  	
	// set and get
}

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/3
 * @description DAO 接口
 */
public interface ClassDao {
  public List findAll();
}

<&＃63;xml version="1.0" encoding="UTF-8" &＃63;>


  
    
    
    
    
      
      
      
      
      
    
  
  
    select * from student s, class c where s.c_id = c.c_id
  

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/3
 * @description 测试类
 */
public class MybatisDemo {

  @Test
  public void TestA() throws IOException {
    // 加载核心配置文件
    InputStream resourceAsStream = Resources.getResourceAsStream("mybatis.xml");
    // 获得 sqlSession 工厂对象
    SqlSessionFactory sqlSessiOnFactory= new SqlSessionFactoryBuilder().build(resourceAsStream);
    // 获得 sqlSession 对象
    SqlSession sqlSession = sqlSessionFactory.openSession();

    List list = sqlSession.selectList("com.software.mybatis.dao.ClassDao.findAll");

    for (Class aClass : list) {
      System.out.println(aClass);
    }
  }

}

public class Course {
  private Integer cId;
  private String cName;
  private List students;
	
	// set and get
}

public class Student {
  private Integer sId;
  private String sName;
  private Long sAge;
  private String sSex;
  private List courses;

	// set and get
}

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/3
 * @description course DAO 接口
 */
public interface CourseDao {
  public List findAll();
}

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/3
 * @description student DAO 接口
 */
public interface StudentDao {
  public List findAll();
}

<&＃63;xml version="1.0" encoding="UTF-8" &＃63;>


  
    
    
    
    
    
      
      
    
  
  
    select * from course c, student s, s_c sc where c.c_id = sc.c_id and s.s_id = sc.s_id
  

<&＃63;xml version="1.0" encoding="UTF-8" &＃63;>


  
    
    
    
      
      
      
      
    
  
  
    select * from course c, student s, s_c sc where c.c_id = sc.c_id and s.s_id = sc.s_id
  

/**
 * Created with IntelliJ IDEA.
 *
 * @author Demo_Null
 * @date 2020/9/3
 * @description 测试类
 */
public class MybatisDemo {

  @Test
  public void TestA() throws IOException {
    // 加载核心配置文件
    InputStream resourceAsStream = Resources.getResourceAsStream("mybatis.xml");
    // 获得 sqlSession 工厂对象
    SqlSessionFactory sqlSessiOnFactory= new SqlSessionFactoryBuilder().build(resourceAsStream);
    // 获得 sqlSession 对象
    SqlSession sqlSession = sqlSessionFactory.openSession();

    List courseList = sqlSession.selectList("com.software.mybatis.dao.CourseDao.findAll");
    List studentList = sqlSession.selectList("com.software.mybatis.dao.StudentDao.findAll");

    System.out.println("### 课程 ###");
    for (Course course : courseList) {
      System.out.println(course);
    }

    System.out.println("### 学生 ###");
    for (Student student : studentList) {
      System.out.println(student);
    }
  }
}