public function listTableColumns($table, $database = null)
    {
        if (! $database) {
            $database = $this->_conn->getDatabase();
        }

        $sql = $this->_platform->getListTableColumnsSQL($table, $database);

        $tableColumns = $this->_conn->fetchAll($sql);

        return $this->_getPortableTableColumnList($table, $database, $tableColumns);
    }