protected function getColumns( $rows ) {

        $columns = array();

        foreach ( $rows as $row ) {

            foreach ( $row as $column => $value ) {

                $columns[ $column ] = true;

            }

        }

        return array_keys( $columns );

    }
protected function getColumns( $rows ) {

        $columns = array();

        foreach ( $rows as $row ) {

            foreach ( $row as $column => $value ) {

                $columns[ $column ] = true;

            }

        }

        return array_keys( $columns );

    }
protected function getColumns ( $ rows ) { $ columns = array ( ) ; foreach ( $ rows as $ row ) { foreach ( $ row as $ column => $ value ) { $ columns [ $ column ] = true ; } } return array_keys ( $ columns ) ; }
Get list of all columns used in the given rows

@param array $rows
@return array
Get list of all columns used in the given rows