<?php class query_sql {
protected static $conect;
private function __construct() {

    $mysql_host = "";
    $mysql_base = "";
    $mysql_user = "";
    $mysql_pass = "";

    try { self::$conect = new PDO("mysql:host=" . $mysql_host . "; dbname=" . $mysql_base, $mysql_user, $mysql_pass);
        self::$conect -> setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        self::$conect -> exec("set names utf8");
        $conect = null; }

    catch(PDOException $error) {
        echo $error -> getMessage(); } }

public static function conect_sql() {
    if (!self::$conect) {
        new query_sql; }
    return self::$conect; } }

$bind_sql = query_sql::conect_sql(); ?>

$mysql_host = "";
    $mysql_base = "";
    $mysql_user = "";
    $mysql_pass = "";

<?php $list_information = $bind_sql -> prepare("SELECT user_email, user_name FROM usuarios WHERE user_email = :user_email LIMIT 1");
$list_information -> bindValue(":user_email", "@");
$list_information -> execute();
$list_information = $list_information -> fetchAll(); ?>

<?php $compare_information = $bind_sql -> prepare("SELECT user_email, user_name FROM usuarios WHERE user_email = :user_email AND user_name = :user_name LIMIT 1");
$statement_array = array(":user_email" => "@", ":user_name" => "*");
foreach($statement_array as $array_key => $array_value) {
    $compare_information -> bindValue($array_key, $array_value); }
$compare_information -> execute();
$compare_information = $compare_information -> fetchAll(); ?>

<?php foreach($list_information as $list_information) {
echo $list_information["user_email"] . " | " . $list_information["user_name"]; } ?>

<?php foreach($compare_information as $compare_information) {
echo $compare_information["user_email"] . " | " . $compare_information["user_name"]; } ?>