* @property integer $id
* @property string $chapter
* @property string $question
* @property string $answer

现在我的actionIndex函数看起来像

public function actionIndex()
{

    $faq = Faq::find()->all();

    $dataProvider = new ActiveDataProvider([
        'query' => Faq::find(),]);

    return $this->render('index',[
        'dataProvider' => $dataProvider,'faq' => $faq
    ]);
}

如何在Controller中使用Yii2或PHP获取$chapter的唯一值数组？让我们说在sql看起来像

SELECT DISTINCT chapter FROM’faq_table’