private function _select($column)
    {
        if ($column === 'all' || $column == '*') {
            $this->selectColumns = $this->quoteIdentifier(
                    self::cyrus()->getTableName()
                ).'.*';
        } else {
            if (string_has($column, 'as') || string_has($column, 'AS')) {
                return $this->selectExpr($column);
            }

            $this->selectColumns = (string) str_replace(' ', '', $this->quoteIdentifier(explode(',', $column)));
        }

        return $this;
    }