protected function dbInsert($category, $key, $value)
    {
        $created_by = \Yii::$app->user->getId();
        $this->getDb()->createCommand('
        INSERT INTO
            {{setting}} (`category`, `key`, `value`, `created_at`, `created_by`)
        VALUES
            (:category, :key, :value, NOW(), :created_by)
        ', compact('category', 'key', 'value', 'created_by'))->execute();
    }