mybatis plus一对多查询（经典案例）

一、条件

• 查询班级表 返回所有学生信息  （一对多问题）

二、数据库

班级class_info

学生student

二、代码实现

实体类ClassInfo.java

@Data
public class ClassInfo {

    private Long id;
    private String name;
    private String nameTest;

    private List studentList;
}

ClassInfoMapper.xml

    

    
    
        
                         
    

    
        select * from class_info
    

关联StudentMapper.xml中的子查询

 
        SELECT
           *
        FROM
            student s
        where class_info_id = #{id1} or name = #{name}
    

ClassInfoMapper.java

public interface ClassInfoMapper extends BaseMapper {


    IPage listAllWithStudent(IPage page);

}

ClassInfoService.java

public interface ClassInfoService extends IService {

    IPage listAllWithStudent(IPage page);

}

ClassInfoServiceImpl.java

@Service
public class ClassInfoServiceImpl extends ServiceImpl implements ClassInfoService {
    @Autowired
    private StudentService studentService;
    @Override
    public IPage listAllWithStudent(IPage page) {
        return this.baseMapper.listAllWithStudent(page);
    }
}

ClassInfoController.java

@Controller
@RequestMapping("classInfo")
public class ClassInfoController {

    @Autowired
    private ClassInfoService classInfoService;

    @RequestMapping("listAllWithStudent")
    @ResponseBody
    public IPage listAllWithStudent(Integer pageNo,Integer pageSize){
        Page page = new Page<>(pageNo,pageSize);
        return classInfoService.listAllWithStudent(page);
    }

}