The original manage_user_prune.php code:

    # Delete the users who have never logged in and are older than 1 week
$days_old = 7;
$days_old = (integer)$days_old;
$query = "SELECT id
        FROM $t_user_table
        WHERE login_count=0 AND TO_DAYS(".db_now().") - '$days_old' > TO_DAYS(date_created)";
$result = db_query($query);

$count = db_num_rows( $result );

The newer version using db_helper_compare_days:

    # Delete the users who have never logged in and are older than 1 week
$days_old = 7;
$days_old = (integer)$days_old;
$date_calc = db_helper_compare_days(db_now(),"date_created","> $days_old");     
$query = "SELECT id
        FROM $t_user_table
            WHERE login_count=0 AND $date_calc";

$result = db_query($query);

$count = db_num_rows( $result );

The latest version using ADODB:

    # Delete the users who have never logged in and are older than 1 week
$days_old = 7;
$days_old = (integer)$days_old;
global $g_db;
$date_calc = $g_db->OffsetDate(-7) . "> date_created";

$query = "SELECT id
        FROM $t_user_table
                WHERE login_count=0 AND $date_calc";

$result = db_query($query);

$count = db_num_rows( $result );