public function addCode($tableName, $columnName = 'code')
    {
        $this->addColumn('{{%' . $tableName . '}}', $columnName,
            $this->string(32)->comment('Code for this item, used identifying when needed. Another criteria to replace ID because ID is auto-increment'));
        $this->createIndex($tableName . '_' . $columnName . '_idx', '{{%' . $tableName . '}}', $columnName);
    }