php - 警告：mysql_result()：无法跳转到 MySQL 结果索引的第 0 行

Question

可能重复：
MySQL - 无法跳转到 MySQL 结果索引的第 0 行

我收到 mysql_result(): Unable to jump to row 0 错误。不知道下面的函数有什么问题

function update_counter($post_id){
    global $wpdb;       
    $query = "SELECT view_count FROM ".$wpdb->prefix."advert_views WHERE postid = $post_id";
    if(@$query_run = mysql_query($query)){
        $count = mysql_result($query_run, 0, 'view_count' );
        $count_inc = $count + 1;
        $query_update = "UPDATE ".$wpdb->prefix."advert_views SET view_count = $count_inc WHERE postid = $post_id";
        if(@$query_update_run = mysql_query($query_update)){
            echo 'OK';
        }
    }
}

---

好的，我用下面的代码修改了函数，错误消失了。只是参考其他问题。但我无法正确理解逻辑。任何人都可以帮助我理解实际 > 0 的逻辑吗？

function update_counter($post_id){
    global $wpdb;
    $query = "SELECT view_count FROM ".$wpdb->prefix."advert_views WHERE postid = $post_id";
    $query_run = mysql_query($query);
    if(mysql_num_rows($query_run) > 0) {
        $count = mysql_result($query_run, 0, 'view_count' );
        $count_inc = $count + 1;
        $query_update = "UPDATE ".$wpdb->prefix."advert_views SET view_count = $count_inc WHERE postid = $post_id";
        if(@$query_update_run = mysql_query($query_update)){
            echo 'OK';
        }
    }
}