$pdo = new PDO('mysql:host=localhost;dbname=database', 'username', 'password');
$ps = $pdo->prepare("SELECT * FROM wp_users WHERE user_login = ?");
$ps->execute(array($_GET["user_login"]));
$result = $ps->fetch(PDO::FETCH_ASSOC);
      /*extract($result);*/

var_dump($result);

include ("theme/header-main.html");

    $pdo = new PDO('mysql:host=localhost;dbname=database', 'username', 'password');
    $ps = $pdo->prepare("SELECT * FROM wp_users WHERE user_login = ?");
    if (!empty($_GET["user_login"])) {
        $ps->execute(array($_GET["user_login"]));
    } else {
        header('location: index.php');
    }

    $result = $ps->fetch(PDO::FETCH_ASSOC);

    if (is_array($result)) {
        extract($result);

        include('TESTuser-content.php');

    } else {
        include('user-content-search.php');
    }

include ("theme/footer-main.html");

$pdo = new PDO('mysql:host=localhost;dbname=database', 'username', 'password');
$ps = $pdo->prepare("SELECT user_login FROM wp_users WHERE user_login = ?");
$result = $ps->fetchall();

<?php foreach($result as $row){echo $row[0]} ?>