php 致命错误：调用未定义的函数 mysqli_connect()
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Fatal error: Call to undefined function mysqli_connect()
提问by Emi
For 2 days now I'm trying to solve this, but unfortunately no result. Let me tell you my story about the problem. I've bulid an application on a site, and the application deals with the reviews. But, I'm trying to put it on another site, and I copyed the php files, the sql file from the old site, and moved them to the new site (they are on different FTP servers). When I'm trying to go to the pages from the application, I receive this FATAL ERROR:
现在 2 天了，我试图解决这个问题，但不幸的是没有结果。让我告诉你我关于这个问题的故事。我在网站上构建了一个应用程序，该应用程序处理评论。但是，我试图把它放在另一个站点上，我从旧站点复制了 php 文件和 sql 文件，并将它们移动到新站点（它们位于不同的 FTP 服务器上）。当我尝试从应用程序转到页面时，我收到此致命错误：
Fatal error: Call to undefined function mysqli_connect()
致命错误：调用未定义的函数 mysqli_connect()
The code that I wrote to connect to the database is this (with hidden credentials):
我编写的连接数据库的代码是这样的（带有隐藏的凭据）：
$con = mysqli_connect("","*the_name*","*the_pass*","*the_database*");
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
Why do I get the error? It works on the old server, and the code I think it's not the problem, because it works on localhost, and on the new server it doesn't. Can anyone help me?
为什么我收到错误？它在旧服务器上工作，我认为代码不是问题，因为它在本地主机上工作，而在新服务器上却没有。谁能帮我？
回答by Dave O'Dwyer
If you host the server yourself, in the php.inifile remove the semicolon in front of the extension extension=php_mysqli.dll
如果您自己托管服务器，请在php.ini文件中删除扩展名 extension=php_mysqli.dll前面的分号
回答by Jo?o Pimentel Ferreira
Simply do it
简单地做
sudo apt install php-mysqli
sudo apt install php-mysqli
It works perfectly and it is version independent
它完美运行并且与版本无关
回答by Rehmat
On Ubuntu I had to install php5 mysql extension.
在 Ubuntu 上，我必须安装 php5 mysql 扩展。
apt-get install php5-mysql
apt-get 安装 php5-mysql
回答by RemyG
Happens when php extensions are not being used by default. In your php.ini file, change;extension=php_mysql.dll
to extension=php_mysql.dll.
**If this error logs, then add path to this dll file, egextension=C:\Php\php-???-nts-Win32-VC11-x86\ext\php_mysql.dll
Do same for php_mysqli.dlland php_pdo_mysql.dll. Save and run your code again.
默认情况下未使用 php 扩展时发生。在 php.ini 文件中，更改;extension=php_mysql.dll
为extension=php_mysql.dll.
**如果此错误记录，则添加此 dll 文件的路径，例如，extension=C:\Php\php-???-nts-Win32-VC11-x86\ext\php_mysql.dll
对php_mysqli.dll和执行相同操作php_pdo_mysql.dll。保存并再次运行您的代码。
回答by Jahmic
Late to the conversation...
谈话迟到...
If you have the module installed and set your PHP.INI file properly, check your apache error log for something like the following:
如果您安装了该模块并正确设置了您的 PHP.INI 文件，请检查您的 apache 错误日志中的类似内容：
PHP Warning: PHP Startup: Unable to load dynamic library 'C:\php\ext\php_mysqli.dll' - The specified module could not be found.
PHP 警告：PHP 启动：无法加载动态库 'C:\php\ext\php_mysqli.dll' - 找不到指定的模块。
In this case, your extension directory is not what you think it is. You may neeed to set it explicitly, like so:
在这种情况下，您的扩展目录不是您认为的那样。您可能需要明确设置它，如下所示：
extension_dir="C:\xampp\php\ext"
回答by doapydave
Mine was a bit different for php7 on centos7.
对于centos7上的php7，我的有点不同。
In /etc/php.ini
在 /etc/php.ini
; extension=mysqli
; 扩展名=mysqli
to
到
extension=mysqli
扩展名=mysqli
回答by Yu Jiaao
if you use ubuntu 16.04 (maybe and above),you have this module already but not enabled by default. Just do this:
如果您使用 ubuntu 16.04（可能及更高版本），则您已经拥有此模块，但默认情况下未启用。只需这样做：
sudo phpenmod mysqli
回答by AaronDanielson
If you host the server yourself, and that server happens to be Apache, you can also get this error even if you have uncommented extension=php_mysqli.dllin php.ini.
如果您自己托管服务器，并且该服务器恰好是 Apache，那么即使您extension=php_mysqli.dll在 php.ini 中取消注释，您也会收到此错误。
You also need to tell Apache where to find php.ini by using the PHPIniDirdirective in Apache's httpd.conf
您还需要使用PHPIniDirApache 的 httpd.conf 中的指令告诉 Apache 在哪里可以找到 php.ini
AddHandler application/x-httpd-php .php
PHPIniDir "<path-to-folder-where-php-ini-lives>"
回答by Utkarsh Dixit
There is no error in the, but the mysqli PHP extension is not installed on your machine. Please contact your service provider to fix this issue.
中没有错误，但是您的机器上没有安装mysqli PHP 扩展。请联系您的服务提供商以解决此问题。
