Php/MySQL插入记录查询错误？

Question

我有一个名为database.php中包含以下内容：

<?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(); 
} 


?> 

我有一个名为functions.php的新文件，其中包含以下内容：

<?php 

// Functions file for the system 

function add_post($user_id, $body) { 
    $post = "INSERT INTO posts (user_id, body, stamp) VALUES ($user_id, $body, now())"; 
    $insert_post = "mysqli_query($connection, $post)"; 
} 

?> 

和插入后PHP页面（ newPost.php），其包含以下内容：

<?php 

// Define the user id and get the post from the form 
$user_id = 1; // User ID hard coded for testing purposes 
$body = substr($_POST['body'],0,200); 

// Insert the post in the database using the add_post() function 

if (isset($user_id, $body) && ($_SERVER['REQUEST_METHOD'] == 'POST')) { 

    // Insert the post in the database if conditions were met 
    add_post($user_id, $body); 
    } 
    // If the conditions were not met, display an error 
    else { 
     die("The post was not added. Something went wrong. Please try again later"); 
    } 
?> 

当我尝试发布一些文字，我得到以下错误：

注意：未定义的变量：连接在/Applications/MAMP/htdocs/blog/includes/functions.php第7行

我在这里做错了什么？不是$连接应该被传递，因为我使用require（）;在我的newPost.php文件？

Answer 1

这是一个variable scope的问题。

function add_post($user_id, $body, $connection) { 
    $post = "INSERT INTO posts (user_id, body, stamp) VALUES ($user_id, $body, now())"; 
    $insert_post = mysqli_query($connection, $post); 
} 

您也可以使用关键字global，但通常被认为是一种不好的做法，应该避免：$connection除非你把它作为一个参数不提供给add_post()。

Answer 2

这是完全错误的：

$insert_post = "mysqli_query($connection, $post)"; 
       ^---        ^-- 

你不执行查询。你正在定义一个恰好包含一些文本的字符串，就像查询调用那样。删除引号...

Answer 3

上面的答案应该让它为你工作，但考虑使用mysqli准备语句，而不是mysqli_query。准备好的语句更安全，并通过用户输入来防止sql注入。