DB中的条目数 [英] Number of entries in DB PHP

问题描述

我创建一个函数来显示有多少用户现在在线。这是基于谁在过去5分钟内打开了一个页面。每个网页载入都会保存到我的数据库中，如下所示：

I am creating a function to show how many users are online now. This is based on who has opened a page within the last 5 min. Each page load is saved to my DB, below:

目前我有以下代码

$query = mysql_query("SELECT user_id, timestamp FROM user_actions WHERE timestamp > date_sub(now(), interval 5 minute)");
        $onlineUsers = mysql_num_rows($query); 

这只是总计行数，我如何做到这一点， ？ （因此在上面的数据库片段应该是2不是5）

This is simply totalling the number of rows, how can I do this so it only counts a user_id once? (so in the above database snippet it should be 2 not 5)

推荐答案

由于 mysql _ * 已弃用（php 5以上）并在（php 7）中移除。因此， mysqli _ * 示例如下： -

Since mysql_* is deprecated (php 5 onward) and removed in (php 7). So a mysqli_* example is here:-

<?php

error_reporting(E_ALL);
ini_set('display_errors',1);

$conn = mysqli_connect('localhost','username','password','db name');//change credentials here
$online_users = array();
if($conn){

    $query = mysqli_query($conn,"SELECT DISTINCT(user_id), timestamp,page FROM user_actions WHERE timestamp > date_sub(now(), interval 5 minute)");

    if($query){
        while($row = mysqli_fetch_assoc($query)){
            $online_users[] = $row;
        }
    }else{
        echo "query error:-".mysqli_error($conn);
    }
}else{
    echo "db connection error:-".mysqli_connect_error();
}

?>
<table>

<tr>
    <thead>
        <th>User Id</th>
        <th>timestamp></th>
        <th>Page Visited</th>
    </thead>
</tr>
<tbody>
    <?php foreach($online_users as $online_user){?<
            <tr>
                <td><?php echo $online_user['user_id'];?></td>
                <td><?php echo $online_user['timestamp'];?></td>
                <td><?php echo $online_user['page'];?></td>
            </tr>
    <?php }?>
</tbody>
</table>

注意： - 如果你想显示在线用户名，那么你必须做 JOIN query 。

Note:- If you want to show online user name also then you have to do JOIN query.

因此更改表格代码。

码。相应地修改它。

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