Planet CakePHP

I'm trying to group by date of birth and count based on the results, using CakePHP. Here's my query.

$data = $this->User->find('all', array(
    'fields' => array(
        "DATE_FORMAT(NOW(), '%Y') - DATE_FORMAT(User.dob, '%Y') - (DATE_FORMAT(NOW(), '00-%m-%d') < DATE_FORMAT(User.dob, '00-%m-%d')) AS age",
        'COUNT(id)'
    ),
    'group' => 'age'
));

So far, so good. The field User.dob is date of birth, it's a DATETIME field.

Thing is, it returns something like this:

Array
(
    [0] => Array
        (
            [0] => Array
                (
                    [age] => 9
                    [COUNT(id)] => 1
                )

        )

    [1] => Array
        (
            [0] => Array
                (
                    [age] => 10
                    [COUNT(id)] => 1
                )

        )

    [2] => Array
        (
            [0] => Array
                (
                    [age] => 11
                    [COUNT(id)] => 1
                )

        )

    [3] => Array
        (
            [0] => Array
                (
                    [age] => 12
                    [COUNT(id)] => 8
                )

        )

    [4] => Array
        (
            [0] => Array
                (
                    [age] => 13
                    [COUNT(id)] => 1
                )

        )

Surely there must be a better way.

And I can't even filter it. This code throws error. Unknown column 'age'

$data = $this->User->find('all', array(
    'conditions' => array('age >' => 20),
    'fields' => array(
        "DATE_FORMAT(NOW(), '%Y') - DATE_FORMAT(User.dob, '%Y') - (DATE_FORMAT(NOW(), '00-%m-%d') < DATE_FORMAT(User.dob, '00-%m-%d')) AS age",
        'COUNT(id)'
    ),
    'group' => 'age'
));

By the way, these are the queries.

SELECT DATE_FORMAT(NOW(), '%Y') - DATE_FORMAT(User.dob, '%Y') - (DATE_FORMAT(NOW(), '00-%m-%d') < DATE_FORMAT(User.dob, '00-%m-%d')) AS age, COUNT(id) FROM `users` AS `User` WHERE 1 = 1 GROUP BY age 

(The age calculation routine was found in matt's blog.)