连表查询的简单方法！！

在主表（Appointment）里面private+副表的对象

private Department（副表） depa;

private User（副表） u;

然后source set get

再在主表service层里面

@Autowired
private AppointmentMapper appointmentMapper;
@Autowired
private DepartmentMapper departmentMapper;
@Autowired
private UserMapper userMapper;

//查询全部事件

public List<Appointment> getallapplist(){

for (Appointment ap : appointmentMapper.getlist()) {
ap.setDepa(departmentMapper.selectByPrimaryKey((Integer.valueOf(ap.getDepartment()))));
ap.setU(userMapper.selectByPrimaryKey((Integer.valueOf(ap.getUser()))));
}

return appointmentMapper.getlist();
}