使用 require_once() 函数时 PHP 和 Mysql 连接错误？

Question

这个问题已经有答案了:

PHP code is not being executed, but the code shows in the browser source code (36 个回答)

Are PHP short tags acceptable to use? (28 个回答)

已关闭 4 年前。

config.php

<?
// Database Constants 
define("DB_SERVER", "localhost");
define("DB_USER", "gallery");
define("DB_PASS", "phpOTL123");
define("DB_DATABASE", "photo_gallery");
?>

database.php

<?php
require_once('config.php'); 
class  MySQLDatabase
{
private $connection;
        public function open_connection() {
        $this->connection = mysqli_connect(DB_SERVER, DB_USER, DB_PASS,DB_NAME);
        if (!$this->connection) {
            die("Database connection failed: " . mysqli_error());
        }
        }
    }
$database=new MySQLDatabase();
$database->open_connection();  
?>

我正在定义 DB_SERVER 和所有其他的，如您在上面看到的，但由于某种原因，我收到以下错误:

Warning: Use of undefined constant DB_SERVER - assumed 'DB_SERVER' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\photo_gallery\includes\database.php on line 6

Warning: Use of undefined constant DB_USER - assumed 'DB_USER' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\photo_gallery\includes\database.php on line 6

Warning: Use of undefined constant DB_PASS - assumed 'DB_PASS' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\photo_gallery\includes\database.php on line 6

Warning: Use of undefined constant DB_NAME - assumed 'DB_NAME' (this will throw an Error in a future version of PHP) in C:\xampp\htdocs\photo_gallery\includes\database.php on line 6

Warning: mysqli_connect(): php_network_getaddresses: getaddrinfo failed: No such host is known. in C:\xampp\htdocs\photo_gallery\includes\database.php on line 6

Warning: mysqli_connect(): (HY000/2002): php_network_getaddresses: getaddrinfo failed: No such host is known. in C:\xampp\htdocs\photo_gallery\includes\database.php on line 6 Database connection failed: mysqli_error()

Answer 1

PHP 短标签为 recommended against ，因为它们通常是关闭的。

因此，您的 <?没有执行任何操作，并且您的数据库凭据将被视为纯文本而不是 PHP。将其更改为完整的<?php修复它。