我正在编写一个自定义插件，并使用wordpress页面上的短代码调用插件函数。

global $db_handle;

下面声明了类“DBController”全局的句柄。

if (isset($db_handle))

始终返回False。无法找出原因。我还必须澄清，我首先调用“[连接\\u数据库]”，然后调用“[加载\\u下拉内容=”客户“]”任何帮助都将不胜感激！完整代码如下：

global $db_handle;

function vc_connect_to_database()
{
    require_once("dbcontroller.php");       # Instantiate DB COntrolling functions 
    $db_handle = new DBController();
    $connection = $db_handle->connectDB();
    if (!$connection)
    {
        return \'Unable to connect to database\';
    } 
    else
    { 
        return \'<script>alert("Connected to the database successfully.")</script>\';
    #       return \'<h6>"Database connect successful. This is where the customers list will appear"</h6>\';  
    }   
}

function vc_load_dropdown($atts, $content=null)
{
    $atts = shortcode_atts( array(\'content\' => \'customer\'), $atts );
    if ($atts[ \'content\' ] == \'customer\')
    {
        $query = \'SELECT CustomerID, FirstName, LastName FROM customers ORDER BY FirstName, LastName\';
        if (isset($db_handle))
        {
            return \'DB Handle is available\';
        }
        else
        {
            return \'DB Handle is NOT available\';            
        }
#       $results = $db_handle->runQuery($query);
    } 
}

add_shortcode(\'load_dropdown\', \'vc_load_dropdown\');
add_shortcode(\'connect_database\', \'vc_connect_to_database\');