我想从我正在编写的插件中调用一些函数。我通过wordpress页面上的一个快捷码调用插件代码。首先，我只是想弹出一个“警报”窗口，比如说，如果我成功连接到数据库。最终，插件将显示一个接一个的下拉列表，后面的下拉列表将根据前面的选择填充。感谢您的帮助！我的插件中的代码如下：

<?php
/*
Plugin Name: Custom program graphs
Plugin URI: localhost/test/
Description: Creates graphs
Version: 0.1.0
Author: My Cars
*/

require_once("dbcontroller.php");       # Instantiate DB Controlling - WORKS WELL functions 
function vc_connect_to_database()
{
    $db_handle = new DBController();
    $connection = $db_handle->connectDB();
    if (!$connection)
    {
        return \'<h6>\' . "Unable to connect to database." . \'</h6>\';
    } 
    # WORKS WELL IN THE CONDITION ABOVE THIS
    else
    { 
        # FAILS HERE!! HOW CAN I CALL A FUNCTION LIKE alert FROM HERE?
        return window.alert("Connected to the database successfully.");  
    }   
}
add_shortcode(\'connect_database\', \'vc_connect_to_database\');