protected function _columnNames()
    {
        $columns = [];
        foreach ($this->_columns as $col) {
            if (is_string($col)) {
                $col = trim($col, '`[]"');
            }
            $columns[] = $col;
        }

        return $columns;
    }
protected function _columnNames()
    {
        $columns = [];
        foreach ($this->_columns as $col) {
            if (is_string($col)) {
                $col = trim($col, '`[]"');
            }
            $columns[] = $col;
        }

        return $columns;
    }
protected function _columnNames ( ) { $ columns = [ ] ; foreach ( $ this -> _columns as $ col ) { if ( is_string ( $ col ) ) { $ col = trim ( $ col , '`[]"' ) ; } $ columns [ ] = $ col ; } return $ columns ; }
Get the bare column names.

Because column names could be identifier quoted, we
need to strip the identifiers off of the columns.

@return array
Get the bare column names .