PageHelper分页查询出现数据重复

• 原因：pageHelper进行分页时，如果排序字段不唯一或未空，则出现查询结果在不同页出现重复数据，部分数据也会因此查不出来。

• 解决方案：在查询的sql语句中增加或修改order by方法，使其按照id排序

<select id="findAllCars" resultMap="carMap">
    select
           car.id, car_no, car_brand, car_model, car_color, car_load, car_seats, oil_wear, init_mil,
            maintain_mil, maintain_period, engine_num, frame_num, sup_id, purchase_price, purchase_date,
            dept_id, car_state, car.remarks, car.isdisable,
           car_brand.id as cbid, brand_name,
           car_model.id as cmid, car_model.model_name,
            dept.id as did, dept_name,
           current_unit.id as cuid,unit_name
    from car,car_brand,car_model,dept,current_unit
    where
        car.car_brand = car_brand.id
        and car.car_model = car_model.id
        and car.dept_id = dept.id
        and car.sup_id = current_unit.id
    order by car.id
 </select>