如何解决MyBatis分页PageHelper查询返回的数据存在重复?

当我使用MyBatis Pagination PageHelper时,查询返回的结果是重复的。我觉得不应该!,因为当我查询两个表时会影响重复问题。例如,我编写的sql映射文件包含以下代码:

SELECT
    o.id,
    o.uid,
    u.nickname,
    o.order_num,
    o.order_type,
    o.order_price,
    o.pay_type,
    o.order_status,
    o.name,
    o.phone,
    o.delivery_time,
    o.createtime
FROM
    orders AS o,
    water_member AS u

WHERE
    o.order_status = 1
ORDER BY
    o.id
DESC

但它有重复:

取消援助。JAVA

@RestController
public class UnpaidOrderController {

@Autowired
private UnpaidOrderService unpaidOrderService;

@RequestMapping(value = "unpaidorder",method = RequestMethod.GET)
public Object getByPage(@RequestParam(value = "pageNo",  defaultValue = "1")  int pageNo,
                        @RequestParam(value = "pageSize", defaultValue = "3")  int pageSize) {

    Page<UnpaidOrder> list = unpaidOrderService.findByPage(pageNo, pageSize);
    JSONObject jsonObject = new JSONObject();
    jsonObject.put("msg","查询成功");
    jsonObject.put("data",list);
    return jsonObject;
}}

取消帮助OrderMapper。JAVA

@Mapper
public interface UnpaidOrderMapper {
Page<UnpaidOrder> findByPage();
}

取消付费订购服务。JAVA

public interface UnpaidOrderService {
Page<UnpaidOrder> findByPage(int pageNo, int pageSize);}

UnpaidOrderServiceImpl。JAVA

@Service
public class UnpaidOrderServiceImpl implements UnpaidOrderService {
@Autowired
private UnpaidOrderMapper unpaidOrderMapper;
public Page<UnpaidOrder> findByPage(int pageNo, int pageSize) {
    PageHelper.startPage(pageNo,pageSize);
    return unpaidOrderMapper.findByPage();
 }
 }

取消帮助OrderMapper。xml

<mapper namespace="com.zyl.water.mapper.UnpaidOrderMapper">
<!-- 映射订单对象的resultMap -->
<resultMap id="BaseResultMap" type="UnpaidOrder">
    <result column="id" property="id" />
    <result column="uid" property="uid" />
    <result column="nickname" property="nickname" />
    <result column="order_num" property="order_num" />
    <result column="order_type" property="order_type" />
    <result column="pay_type" property="pay_type" />
    <result column="order_status" property="order_status" />
    <result column="name" property="name" />
    <result column="phone" property="phone" />
    <result column="delivery_time" property="delivery_time" />
    <result column="createtime" property="createtime" />
</resultMap>

<!-- 查询未支付订单 -->
<select id="findByPage" resultMap="BaseResultMap">
    SELECT
        o.id,
        o.uid,
        u.nickname,
        o.order_num,
        o.order_type,
        o.order_price,
        o.pay_type,
        o.order_status,
        o.name,
        o.phone,
        o.delivery_time,
        o.createtime
    FROM
        orders AS o,
        water_member AS u

    WHERE
        o.order_status = 1
    ORDER BY
        o.id
    DESC

</select>