$sorgu = mysql_query("SELECT users.*, articles.* FROM users, articles");
while ($veri=mysql_fetch_array($sorgu)) {
$sorgu2 = mysql_fetch_array(mysql_query("Select id, username from users where id='" . $veri['articles.author_id'] . "'"));
echo "Yazar: " . $sorgu2['username'] . "<br>Makale: " . $veri['articles.article_title'];
}