[Velocd]

date() function returns a human readable representation of a timestamp.

So comparing its return value to a timestamp (joindate) is erroneous.

The query you are probably looking for:

PHP Code:

$new_users = $DB_site->query("
    SELECT username, email, languageid, userid, joindate
    FROM " . TABLE_PREFIX . "user
    WHERE joindate >= ".strtotime('2004-10-06')." 
    AND joindate < ".strtotime('2004-10-07')."
    AND usergroupid IN ($ids)
");