以下代码中出现以下错误：“对中的非对象调用成员函数get\\u results（）”：

require_once($_SERVER[\'DOCUMENT_ROOT\'] . $folder . \'/wp-config.php\');
require_once($_SERVER[\'DOCUMENT_ROOT\'] .  $folder . \'/wp-load.php\');
if (!$wpdb) {
$wpdb = new wpdb( DB_USER, DB_PASSWORD, DB_NAME, DB_HOST);
} else {
    global $wpdb;
}

function vendorDatails( $param)
{
    if ((substr ($param, 0, 0)) == \'#\')
    {
        substr($param, 1);
    }

    $order_ids = $wpdb->get_results( 
                                    "
                                     SELECT DISTINCT vendor_id 
                                     FROM $wpdb->lqrhxf_pv_commission 
                                     WHERE order_id = %d
                                    ",
                                        $param
                                );

    foreach ( $order_ids as $order_id )
    {
        echo $order_id->vendor_id;
    }
}

 $order_ids = $wpdb->get_results(