MySQLi无法连接到MariaDB，为什么？

Question

我正在尝试通过PHP中的MySQLi将数据插入MariaDB。 MariaDB和Apache都在同一台计算机上。从上一页提取HTML变量后，我的代码尝试在本地连接到MariaDB，然后执行错误检查。不幸的是，MySQLi没有连接，并且我收到一条错误消息。

我在Windows 8.1上使用开发WAMPserver。我在MySQLi构造函数参数（而不是localhost）中尝试了127.0.0.1，并禁用了防火墙。它没有帮助。

// Connect to database
$db = new mysqli('localhost', 'user', 'password', 'database');

if ($db->connect_errno)
{
    echo 'Error '.$db->connect_errno.$db->connect_error.'. Could not connect to database. Please try again later.'; 
    exit; 
}

这是WAMP的本地安装，并且MariaDB凭据正确。不过，我仍然收到此错误：

( ! ) Warning: mysqli::__construct(): (HY000/2002): No connection could be 
made because the target machine actively refused it. in 
C:\wamp64\www\mysite\createaccount.php on line 30
Call Stack
#   Time    Memory  Function    Location
1   0.0002  410248  {main}( )   ...\createaccount.php:0
2   0.0003  410632  __construct ( ) ...\createaccount.php:30
Error 2002No connection could be made because the target machine actively 
refused it. . Could not connect to database. Please try again later.