如何在PHP脚本中正确隔离元素与SQL表

I run this SQL in my PHP script:

$sql =  "SELECT u.id AS id, ul.meta_value AS lastpaymentdate, rd.meta_value AS noemails 
FROM wp_users u 
LEFT JOIN wp_usermeta rd ON rd.user_id=u.id AND rd.meta_key='noemails' 
LEFT JOIN wp_usermeta ul ON ul.user_id=u.id AND ul.meta_key='lastpaymentdate' 
WHERE u.user_email = 'testemail@domain.com'";

$rs = $db->Execute($sql);

Here is the data that it would output if I ran it in a SQL console:

+------+-----------------+----------+
|  id  | lastpaymentdate | noemails |
+------+-----------------+----------+
  2523      2013-10-30        0

I need to get the lastpaymentdate (2013-10-30) into the array $lastRenewalDateParts.

What I've come up with is:

$lastRenewalDateParts = explode('-', $rs->data[0][1]);

However, its not working properly. It's giving me an empty array. Where could I be going wrong?

EDIT: Here is the result of print_r($rs):

mysqli_driver_ResultSet Object
(
    [connectionId] => mysqli Object
        (
            [affected_rows] => 1
            [client_info] => 5.5.30
            [client_version] => 50530
            [connect_errno] => 0
            [connect_error] => 
            [errno] => 0
            [error] => 
            [field_count] => 3
            [host_info] => Localhost via UNIX socket
            [info] => 
            [insert_id] => 0
            [server_info] => 5.5.38-35.2
            [server_version] => 50538
            [stat] => Uptime: 2030485  Threads: 19  Questions: 2452324326  Slow queries: 6246  Opens: 22784920  Flush tables: 1  Open tables: 16800  Queries per second avg: 1207.752
            [sqlstate] => 00000
            [protocol_version] => 10
            [thread_id] => 44573449
            [warning_count] => 0
        )

    [fields] => Array
        (
            [id] => 2523
            [lastpaymentdate] => 2013-10-30
            [noemails] => 0
        )

    [resultId] => mysqli_result Object
        (
            [current_field] => 0
            [field_count] => 3
            [lengths] => Array
                (
                    [0] => 4
                    [1] => 10
                    [2] => 1
                )

            [num_rows] => 1
            [type] => 0
        )

    [_currentRow] => 0
    [_numOfRows] => 1
    [_numOfFields] => 3
    [fetchMode] => 1
    [EOF] => 
    [record] => Array
        (
        )

)

I went about accessing the data incorrectly. My original attempt was coming up empty:

echo $rs->data[0][1];

The correct way to access the date field:

echo $rs->fields[lastpaymentdate];

Thank you Jay!