一、通过映射配置文件实现多表联查

首先，使用Mysql数据库，创建两个表，分别为学生表Student表和班级表Class表，在Student表中添加列classid参照主表的列id的外键约束。

学生表Student表：

班级表Class表 ：

现在去写Dao层和实体类

Student实体类：

package com.ape.bean;

import java.util.Date;

public class Student {
    private Integer sid;
    private String sname;
    private Date birthday;
    private String ssex;
    private int classid;
/*
    一对一
*/
    private Classs banji;

    public Student() {
        super();
        // TODO Auto-generated constructor stub
    }

    public Student(Integer sid, String sname, Date birthday, String ssex, int classid, Classs banji) {
        this.sid = sid;
        this.sname = sname;
        this.birthday = birthday;
        this.ssex = ssex;
        this.classid = classid;
        this.banji = banji;
    }

    public Integer getSid() {
        return sid;
    }

    public void setSid(Integer sid) {
        this.sid = sid;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSsex() {
        return ssex;
    }

    public void setSsex(String ssex) {
        th