Why might count in a model not work correctly in Yii?

Question

MySQL

I make a simple request:

$criteria = new CDbCriteria();
$criteria->addCondition('t.user_id = :uid OR company.id IN (:cid)');
$criteria->with = array('company' => array('select' => 'Name'));
$criteria->params = array(':uid' => Yii::app()->user->id, ':cid' => implode(', ', $arCID));
Bill::model()->count($criteria)

From which it turns out:

SELECT COUNT(DISTINCT `t`.`id`) FROM `o_bills` `t` LEFT OUTER JOIN `o_company` `company` ON (`t`.`companyId`=`company`.`id`) WHERE (t.user_id = :uid OR company.id IN (:cid))

and this code returns 10 positions
Made the same query directly to the database, got 25 records. I thought that maybe I'm working directly with another database (copy), for the test I added a record to the database, I got 11 from Yii and 26 from the muscle directly, deleted 3 records -> Yii = 10 , Mysql = 23 .
There are no default expressions in the model that could attach to the request and affect the result, but just in case, I got into the code in the very place where the request goes to the database ( Github per line ) displays the same value! What could it be?
Solution:
I rewrote the query like this, in fact the same SQL is obtained, but it works correctly. What is the catch and did not understand!

$criteria = new CDbCriteria();
$criteria->addInCondition('company.id', $arCID);
$criteria->addCondition('t.user_id = :uid', 'OR')->params[':uid'] = Yii::app()->user->id;
$criteria->with = array('company' => array('select' => 'Name'));

Answer 1

Yii does not count the number of raw rows returned, but the number of Bill models returned.

Answer 2

as an option, not all records in the database have fields filled in, which are indicated as mandatory in the model. In this case, the framework will ignore them, as far as I remember.