<?php
$hostname = 'somehost';
$username = 'someuser';
$password = 'somepasswd';

try {
    $dbh = new PDO("mysql:host=$hostname;dbname=areautenti", $username, $password);
    $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $user = $_POST['user'];
    $id = $_POST['id'];
    $content = $_POST['content'];

    $table = "sitecontent_".$user;

    $stmt = $dbh->prepare("UPDATE $table SET content = :content WHERE id= :id");

    $stmt->bindParam(':content', $content, PDO::PARAM_*);
    $stmt->bindParam(':id', $id, PDO::PARAM_INT, 5);

    $stmt->execute();

    $result = $stmt->fetchAll();

    $dbh = null;
}
catch(PDOException $e)
    {
    echo $e->getMessage();
    }
?>