[Wiki] Use CGridview to sort and filter CSqlDataProvider - when used with UNRELATED tables (or complex queries)

public $gv_hospitals = null;
 
public function rules()
{
    return array(
        ...
        array('gv_hospitals', 'safe', 'on'=>'search'),
    );
}
 
public function search()
{
    $count=Yii::app()->db->createCommand(
        'SELECT COUNT(*) FROM
        tbl_hosp, tbl_dept')->queryScalar();
 
    // If gv_hospitals was received from CGridview, then
    // filter records with a WHERE clause
    if( ($this->gv_hospitals !== null) && 
        ($this->gv_hospitals !== ''))
    {
        // The LIKE operator in the WHERE clause acts the same
        // as this line in Relational Query:
        // $criteria->compare('hosp_name',$this->gv_hospitals,true);
        $sql="
        SELECT
        concat(tbl_hosp.hosp_id, tbl_dept.dept_id) AS compkey,
        tbl_hosp.hosp_id    AS hosp_id,
        tbl_hosp.hosp_name  AS hosp_name,
        tbl_dept.dept_name  AS dept_name
 
        FROM
        tbl_hosp, tbl_dept
 
        WHERE
        tbl_hosp.hosp_name LIKE '%" . $this->gv_hospitals . "%'";
    }
    else
    {
        $sql="
        SELECT
        concat(tbl_hosp.hosp_id, tbl_dept.dept_id) AS compkey,
        tbl_hosp.hosp_id    AS hosp_id,
        tbl_hosp.hosp_name  AS hosp_name,
        tbl_dept.dept_name  AS dept_name
 
        FROM
        tbl_hosp, tbl_dept";
    }
 
    return new CSqlDataProvider($sql, array(
 
        // Use the composite key to keep the (hidden) key values of your
        // gridview rows unique,
        // because functions like getChecked() return key values of
        // checked ROWS - not the id or value of the checkboxes.
        'keyField' => 'compkey',
 
        'totalItemCount'=>$count,
 
        'sort' => array(
 
            // Indicate what can be sorted
            'attributes' => array(
                'gv_hospitals'=>array(
                     'asc' =>'hosp_name ASC,  dept_name ASC',
                     'desc'=>'hosp_name DESC, dept_name ASC',
                ), 
                'dept_name',
            ),
 
            // Default order in CGridview
            'defaultOrder' => array( 
                'gv_hospitals' => CSort::SORT_ASC,
                'dept_name' => CSort::SORT_ASC,
            ),
        ),
 
        'pagination'=>array(
            'pageSize'=>$count, //Show all records
        ),
    )); 
}

array(
 
    array(
        'header'=> 'Hospitals',
        'name'  => 'gv_hospitals',
        'value' => '$data["hosp_name"]',
        'filter'=> CHtml::activeTextField($model, 'gv_hospitals'),
    ),
 
    array(
        'header' => 'Departments',
        'value'=>'$data["dept_name"]',
    ),
),