PHP函数和MySQL连接

Question

我有存储这样的数据库连接信息一个database.php中的文件：

<?php 

// Database connectivity stuff 

$host  = "localhost"; // Hostname for the database. Usually localhost 
$username = "root"; // Username used to connect to the database 
$password = "root"; // Password for the username used to connect to the database 
$database = "blog"; // The database used 

// Connect to the database using mysqli_connect 
$connection = mysqli_connect($host, $username, $password, $database); 

// Check the connection for errors 
    if (mysqli_connect_errno($connection)) { 
    // Stop the whole page from loading if errors occur 
    die("<br />Could not connect to the database. Please check the settings and try again.") . mysqli_connect_error() . mysqli_connect_errno(); 
} 


?> 

，也是一个functions.php文件具有以下：

<?php 

// Functions file for the system 
function show_posts($user_id) { 
    $posts = array(); 
    $sql = "SELECT body, stamp from posts where user_id = '$user_id' order by stamp desc"; 
    $result = mysqli_query($connection, $sql); 
} 

function show_users() { 
    $users = array(); 
    $sql = "SELECT id, username FROM users WHERE status = 'active' ORDER BY username"; 
    $result = mysqli_query($connection, $sql); 

    while ($data = mysqli_fetch_array($result)) { 
     $users[$data->id] = $data->username; 
    } 
    return $users; 
} 

function following($user_id) { 
    $users = array(); 
    $sql = "SELECT DISTINCT user_id FROM following WHERE follower_id = $user_id"; 
    $result = mysqli_query($connection, $sql); 

    while ($data = mysqli_fetch_assoc($result)) { 
     array_push($users, $data->user_id); 
    } 
    return $users; 
} 

?> 

这两个文件都位于/ includes文件夹中。我现在有一个users.php文件，我想在其中显示用户列表。这里是我的代码，尝试做到这一点：

<?php 

     $users = show_users(); 
     foreach ($users as $key => $value) { 
      echo $key . " " . $value; 
     } 

?> 

我的问题是这样的：

注意：未定义的变量：在 /应用程序连接/ MAMP/htdocs中/博客/包括/上线的functions.php 13

警告：mysqli_query（）预计参数1是mysqli的，NULL给出 在/Applications/MAMP/htdocs/blog/includes/functions.php上线13

警告：mysqli_fetch_array（）预计上 线15

的users.php文件具有需要在/Applications/MAMP/htdocs/blog/includes/functions.php给定的参数1被mysqli_result， 空（'includes/functions.php'）和require（'includes/database.php'）。但不知何故值不是通过？。我究竟做错了什么？请帮助我。我希望这是有道理的。未定义变量的问题发生在每个函数3.

Answer 1

要么将​​$connection变量传递给您的函数，要么将其变为全局函数。

E.g：

function show_posts($connection, $user_id) { 
    $posts = array(); 
    $sql = "SELECT body, stamp from posts where user_id = '$user_id' order by stamp desc"; 
    $result = mysqli_query($connection, $sql); 
} 

OR

function show_posts($user_id) { 
    global $connection; 

    $posts = array(); 
    $sql = "SELECT body, stamp from posts where user_id = '$user_id' order by stamp desc"; 
    $result = mysqli_query($connection, $sql); 
} 

Answer 2

尝试$ GLOBALS，而不是在你的函数$连接[ '连接']。查看更多here