<?php
try
{
$user = 'magento_db';
$pass = 'mypass';

$con = new PDO('mysql:host=localhost;dbname=magento_db', $user, $pass);
foreach($con->query('SELECT * from admin_role') as $row) {
print_r($row);
}
$con = null;
}
catch (PDOEception $e) {
print "Error!: " . $e->getMessage() . "<br/>";
die();
}
?>