[Java知识库]关联数据查询

数据库中的表经常有业务关联关系。

2. 实例

UserVO.java 定义参数，添加getset方法和tostring方法

public class UserVO implements Serializable {
    private int empno;
    private String ename;
    private String dname;
}

UserMapper.xml 定义sql语句

<select id="findUserDepartment" resultType="cn.tedu.vo.UserVO">
        select
            e.empno,
            e.ename,
            d.dname
        from
            emp e
        left join
            dept d
        on
            e.deptno=d.deptno
    </select>

UserMapper.java 定义抽象方法

List<UserVO> findUserDepartment();

测试方法

	@Test
    public void testFindUserDepartment(){
        UserMapper mapper = ctx.getBean("userMapper",UserMapper.class);
        List<UserVO> list = mapper.findUserDepartment();
        list.forEach(u -> System.out.println(u));
    }