Assume that you have teachers and students model.

teacher model has: 
- person_id,
- id_teacher,
- name,
- surname,
- bachelor,
- master,
... etc

student model has: 
- person_id,
- id_student,
- name,
- surname,
- age,
- apartment

(person_id is a global id both of teachers and students)

Now we want a CArrayProvider like that

PERSON DETAILS

person_id, id, name,  surname, bachelor, master, age, apartment

1           1  name1  surname1   yes       no     -       -

2           2  name2  surname2   yes      yes     -       -

3           1  name3  surname3    -        -     23    engineer

4           2  name4  surname4    -        -     25    doctor

5           3  name5  surname5    no      yes    -       -

How to achieve that?

This is a code that I used for a project

$t1 = Teachers::model()->findAll();
        $t2 = Students::model()->findAll();


        //prepair column's header (easy way)
        if (isset($t1[0]))
            $h = array_flip(array_keys($t1[0]->attributes));

        if (isset($t2[0]))
            $h = array_merge($h, array_flip(array_keys($t2[0]->attributes)));

        foreach ($h as $k => $v) {
            $h[$k] = null;
        }

        //collect the data using common key
        $res = array();
        foreach ($t1 as $v) {
            $res[$v->person_id] = $h;
            $res[$v->person_id] = array_merge($h, $v->attributes);
        }

        //merge with second data collection
        $test = 0;
        foreach ($t2 as $v) {
          $res[$v->person_id] = array_merge(isset($res[$v->person_id]) ? $res[$v->person_id] :   array(), $v->attributes);
        }

        //convert to CArrayDataProvider
        $dataProviderCompined = new CArrayDataProvider($res, array(
                    'pagination' => array(
                        'pageSize' => 10,
                    ),
                ));

        

        //display the data on CGridView
        $this->widget('zii.widgets.grid.CGridView', array(
            'id' => 'cost-grid-detail',
            'dataProvider' => $dataProviderCompined,
            'columns' => array(
                'person_id',
                'id',
                'name',
                'surname',
                'bachelor',
                'master',
                'age',
                'apartment'
            ),
        ));