How is a YII statistical query built?

Question

Yii

How to use this statistical query on the same table? No links. And is it even possible?
I re-read the documentation several times and did not find anything.

'type_base' => array(
          self::STAT,
          'keyword',
          'id',
          'select' => 't.type, t.project_id, COUNT(*)',
          'condition' => 't.type='.self::TYPE_BASE.'',
          'group' => 't.type, t.project_id'
        ),