Aggregate function, How to ?!

I needed to get MAX valueid ID field. Problem was that "name" field appeared in the output and "maxID" did not, this is the code:

$criteria=new CDbCriteria;

$criteria->select = 'name, MAX(id) as maxID';

$last = Tree::model()->find($criteria);

echo $last->name;  // this is working !

echo $last->maxID; // error, this field does not exists ! Property "??.maxID" is not defined.

After short time of seach an answer i solved that problem:

$criteria=new CDbCriteria;

$criteria->select = 'name, MAX(id) as id';

$last = Tree::model()->find($criteria);

echo $last->id;

some how id propertie already defined and this at last is overwritten 

Does anybody knows what does this mean "Property "??.maxID" is not defined." ?

In your model class you have to define a maxID variable

class myModelextends CActiveRecord {





public $maxID;


......


}

Overiding $id could be dangerous because if you later save this record you may end up with wrong data in the database