php – 以数字方式排序表并获取列表编号

在我的WordPress网站中,我有自定义用户元数据信誉.该值为数字,与Stackoverflow中的点/信号使用方式类似.

我想得到用户排名的人数.

浏览数据库,我需要做的就是按降序列出表格,我可以看到谁排名为1(最多点)等等……

有什么办法可以向用户显示排名吗？我猜最好的方法是按降序排序表,并以某种方式获取用户在该列表中的位置数量？

我想获取用户的排名.与下面的函数类似,获取用户的总评论数.我需要user_id作为参数：

function get_user_comments_count( $uid ){
    global $wpdb;
    $where = 'WHERE comment_approved = 1 AND user_id = ' . $uid ;
    $comment_count = $wpdb->get_var("SELECT COUNT( * ) AS total 
                FROM {$wpdb->comments}
                {$where}");
    return $comment_count;
}

解决方法:

您可以使用连接作为用户表和元数据,并按列中存储的meta_value进行排序,

SELECT u.* 
FROM `wp_users` u
JOIN `wp_usermeta` um ON(u.ID = um.`user_id`)
WHERE um.`meta_key` = 'reputation'
ORDER BY um.`meta_value` * 1 DESC

按顺序使用* 1是一个简单的转换技巧到整数,desc将按用户的信誉评分列出用户,这样就会首先列出信誉较高的用户,依此类推

global $wpdb;
$query="    SELECT u.*,um.`meta_value` as `rank` 
    FROM $wpdb->users u
    JOIN $wpdb->usermeta um ON(u.ID = um.`user_id`)
    WHERE um.`meta_key` = 'reputation'
    ORDER BY um.`meta_value` * 1 DESC";
$results = $wpdb->get_results($query, OBJECT );

循环搜索结果

foreach($results as $r){
echo $r->rank; // rank of user
}

从评论中编辑

这是你的功能

function getReputationByUser($user_id){
    if(!is_numeric($user_id)){
    return false;
    }
    global $wpdb;
    $query="    SELECT um.`meta_value` as `rank`
        FROM  $wpdb->usermeta um
        WHERE um.`meta_key` = 'reputation'
        AND um.user_id = '".$user_id."'
        ";
    $result  = $wpdb->get_row($query);
    if(!empty($result)){
    return $result->rank;
    }
    return false;
}

echo getReputationByUser(100);

上面的代码用于返回声誉,如果你想要基于声誉的用户等级你可以通过下面的查询得到这个,但我不确定你是否可以在WPDB类中使用@variables of Mysql

SELECT t1.`rank`
FROM(
SELECT 
  um.user_id,
  @rownum:= @rownum + 1 `rank` 
FROM
  wp_usermeta um 
  CROSS JOIN (SELECT @rownum := 0) t 
WHERE um.`meta_key` = 'reputation' 
ORDER BY um.`meta_value` * 1 DESC 
) t1
WHERE t1.user_id = 100

上述查询的功能

function getReputationByUser($user_id){
        if(!is_numeric($user_id)){
        return false;
        }
        global $wpdb;
        $query=" SELECT t1.`rank`
        FROM(
        SELECT
          um.user_id,
          @rownum:= @rownum + 1 `rank`
        FROM
          $wpdb->usermeta um
          CROSS JOIN (SELECT @rownum := 0) t
        WHERE um.`meta_key` = 'reputation'
        ORDER BY um.`meta_value` * 1 DESC
        ) t1
        WHERE t1.user_id = '".$user_id."'";
        $result  = $wpdb->get_row($query);
        if(!empty($result)){
        return $result->rank;
        }
        return false;
}

echo getReputationByUser(100);

这是使用group_concat和find_in_set函数查找用户排名的另一种方法

SELECT user_id,FIND_IN_SET(
              user_id,(SELECT GROUP_CONCAT( user_id ORDER BY meta_value * 1 DESC)  
                      FROM `wp_usermeta` 
                      WHERE meta_key ='reputation')
                   ) AS rank
FROM wp_usermeta
WHERE meta_key ='reputation'
AND user_id = 100

function getReputationByUser($user_id){
        if(!is_numeric($user_id)){
        return false;
        }
        global $wpdb;
        $query="SELECT user_id,FIND_IN_SET(
                      user_id,(SELECT GROUP_CONCAT( user_id ORDER BY meta_value * 1 DESC)
                              FROM $wpdb->usermeta
                              WHERE meta_key ='reputation')
                           ) AS rank
        FROM $wpdb->usermeta
        WHERE meta_key ='reputation'
        AND user_id = '".$user_id."'
        ";
        $result  = $wpdb->get_row($query);
        if(!empty($result)){
        return $result->rank;
        }
        return false;
}

echo getReputationByUser(100);

> group_concat

According to docs The result is truncated to the maximum length that
is given by the group_concat_max_len system variable, which has a
default value of 1024. The value can be set higher, although the
effective maximum length of the return value is constrained by the
value of max_allowed_packet.

标签：wordpress,php,mysql,database,wpdb
来源： https://codeday.me/bug/20190612/1224648.html