php排序算法

功能描述：

　　实现对数据点击[向上][向下]按钮，进行排序功能

数据：

　　数据id：id

　　排序字段：rank_id

if($rankNum>0){
        //echo $id;             //brand_rank
        //echo $rankNum;   //移动到的位置
        //倒序查找前$rankNum个元素
        $rankNum++;
        $query = "SELECT id, brand_rank FROM `#@__archives` WHERE `brand_rank`<={$id} AND `typeid`=28 AND `arcrank`>-1 ORDER BY `brand_rank` DESC limit {$rankNum}";
    }else if($rankNum < 0){
        //echo $id;
        //echo $rankNum;
        //倒序查找后abs($rankNum)个元素
        $rankNum = abs($rankNum);
        $rankNum++;
        $query = "SELECT id, brand_rank FROM `#@__archives` WHERE `brand_rank`>={$id} AND `typeid`=28 AND `arcrank`>-1 ORDER BY `brand_rank` ASC limit {$rankNum};";
    }
    $dsql->SetQuery($query);
    $dsql->Execute();
    while ($row = $dsql->GetArray()){
        $array_id[]=$row["id"];
        $rank_id[] = $row["brand_rank"];
    }
    $count_num = count($array_id);
    $array['data'] = array();
    $j = 0;
    for ($i=1; $i<$count_num; $i++,$j++){
        $query = "UPDATE `#@__archives` SET `brand_rank`={$rank_id[$j]} WHERE `id`={$array_id[$i]}";
        if(!$dsql->ExecuteNoneQuery($query)){
            $array['msg'] = "调整失败，请刷新重试！";
            $array['status'] = 2;
            echo json_encode($array);
            exit();
        }
    }
    $query = "UPDATE `#@__archives` SET `brand_rank`={$rank_id[$j]} WHERE `id`={$array_id[0]}";
    if(!$dsql->ExecuteNoneQuery($query)){
        $array['msg'] = "调整失败，请刷新重试！";
        $array['status'] = 1;
        echo json_encode($array);
        exit();
    }
    $array['msg'] = "调整成功";
    $array['status'] = 0;
    echo json_encode($array);