分页插件返回数量不对的问题

1. 如果是对单表的查询，那么使用分页插件是没有问题的。

2. 如果是有表的关联查询，那么分页插件实际上是对中间表作的一个分页，那么就会造成分页数量不对的问题。

<resultMap id="BaseResultMap" type="com.zzhua.vadmin.entity.Order">
    <result property="userId" column="user_id"></result>
    <result property="createdTime" column="created_time"></result>
    <result property="orderId" column="order_id"></result>
    <result property="orderAddr" column="order_addr"></result>
    <result property="orderFlag" column="order_flag"></result>
    <result property="orderPrice" column="orderPrice"></result>
    <result property="orderTel" column="order_tel"></result>
    <result property="orderPrice" column="order_price"></result>
    <result property="updatededTime" column="updated_time"></result>
</resultMap>

错误示例：

<resultMap id="OrderVoMap" type="com.zzhua.vadmin.vo.OrderVo" extends="BaseResultMap">
    <collection property="orderinfoList" ofType="com.zzhua.vadmin.entity.Orderinfo">
    <result property="orderId" column="order_id"></result>
    <result property="proId" column="pro_id"></result>
    <result property="pcount" column="pcount"></result>
    </collection>
</resultMap>
 
List<OrderVo> queryOrder(@Param("order") Order order, Page page);

// 关联查询，得到中间表。一个订单会包含多个订单详情，那么就会造成中间表，同一个订单算成了2条记录，这样分页就出错了
<select id="queryOrder" resultMap="OrderVoMap">
    select o.*,oi.* from t_order o left join t_orderinfo oi on o.order_id = oi.order_id
    <where>
        <if test="order!=null and order.userId!=null ">
            and o.user_id =#{order.userId,jdbcType=BIGINT}
        </if>
        <if test="order!=null and order.orderId!=null ">
            and o.order_id = #{order.orderId,jdbcType=BIGINT}
        </if>
        <if test="order!=null and order.orderFlag!=null">
            and o.order_flag = #{order.orderFlag,jdbcType=INTEGER}
        </if>
        <if test="order!=null and order.orderTel!=null and order.orderTel!=''">
            and o.order_tel like  CONCAT('%',o.order_tel,'%')
        </if>
    </where>
    order by created_time desc
</select>           
            

正确示例：

<resultMap id="OrderVoMap2" type="com.zzhua.vadmin.vo.OrderVo" extends="BaseResultMap">
    <collection property="orderinfoList"
                ofType="com.zzhua.vadmin.entity.Orderinfo"
                column="order_id"
                select="com.zzhua.vadmin.mapper.OrderinfoMapper.queryOrderinfosByOrderId">
    </collection>
</resultMap>

List<OrderVo> queryOrder2(@Param("order") Order order, Page page);

<select id="queryOrder2" resultMap="OrderVoMap2">
    select * from t_order o
    <where>
        <if test="order!=null and order.userId!=null ">
            and o.user_id =#{order.userId,jdbcType=BIGINT}
        </if>
        <if test="order!=null and order.orderId!=null ">
            and o.order_id = #{order.orderId,jdbcType=BIGINT}
        </if>
        <if test="order!=null and order.orderFlag!=null">
            and o.order_flag = #{order.orderFlag,jdbcType=INTEGER}
        </if>
        <if test="order!=null and order.orderTel!=null and order.orderTel!=''">
            and o.order_tel like  CONCAT('%',o.order_tel,'%')
        </if>
    </where>
    order by created_time desc
</select>
    
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public interface OrderinfoMapper extends BaseMapper<Orderinfo> {
    List<Orderinfo> queryOrderinfosByOrderId(@Param("orderId")Long orderId);
}
<select id="queryOrderinfosByOrderId" resultType="com.zzhua.vadmin.entity.Orderinfo">
    select * from t_orderinfo where order_id = #{orderId}
</select>
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