protected function dropColumn($col)
    {
        if (empty($col)) {
            return Yii::t('podium/flash', 'Installation aborted! Column name missing.');
        }
        try {
            $this->db->createCommand()->dropColumn($this->table, $col)->execute();
            return $this->returnWarning(Yii::t('podium/flash', 'Table column {name} has been dropped', ['name' => $col]));
        } catch (Exception $e) {
            return $this->returnError($e->getMessage(), __METHOD__,
                Yii::t('podium/flash', 'Error during table column {name} dropping', ['name' => $col])
            );
        }
    }