Re: Recursively determine parent records?

[point of no return <pointofnoreturn@xxxxxxxxxxxxx>]

http://www.sitepoint.com/print/hierarchical-data-database
has a guide on how to do the same thing but in a single SQL query, 
without looping at all.  It is very interesting reading and requires a 
slight restructuring of how the records are stored to pull off but with 
the wonderful result in being much faster to retrieve.

Chris Gregors wrote:
> Here's a piece of some code I wrote that does what you want. You'll need
> to change the WhoIsMyParent() function to match your database
> abstraction and schema.
>
> $array = BreadCrumbs($id);
> print_r($array);
> exit;
>
> function BreadCrumbs($parent) {
> 	// construct an array of indexes that represents the path back
> to the
> 	// root from my current location in the tree.
> 	$PathStack = array();
> 	array_push($PathStack,$parent);
> 	$MyParent = WhoIsMyParent($parent);
> 	while ($MyParent != 0) {			// 0 = top of
> the tree
> 		$PathStack[] = $MyParent;
> 		$MyParent = WhoIsMyParent($MyParent);
> 	}
> 	$PathStack = array_reverse($PathStack);
> 	return $PathStack;
> }
>
> function WhoIsMyParent($id) {
> 	$row=FetchRow(QueryDb("select parent from sometable where
> id=".$id));
> 	if ($row == NULL) return 0;
> 	return $row['parent'];
> }
>
> -----Original Message-----
> From: Murray @ PlanetThoughtful [mailto:lists@xxxxxxxxxxxxxxxxxxxx]
> Sent: Tuesday, October 05, 2004 11:58 PM
> To: php-db@xxxxxxxxxxxxx
> Subject:  Recursively determine parent records?
>
>
>  
>
> Hi All,
>
>  
>
> I have recordset that contains a hierarchical representation of records
> where a record's [parentid] field contains the recid of the record
> 'above'
> the current record.
>
>  
>
> A representation might look like this:
>
>  
>
> Recid, parentid, title
>
>  
>
> 1, 0, Top level record
>
> 2, 0, Another top level record
>
> 3, 1, A record under the top level record
>
> 4, 3, Another level
>
> 5, 2, A record under the second top level record
>
>  
>
> If I have currently retrieved the record with recid of 4, I want to work
> out
> the 'chain' of records that lead back to the top level record it has
> been
> created under.
>
>  
>
> In this instance, that chain would look like:
>
>  
>
> 4, 3, Another level
>
> 3, 1, A record under the top level record
>
> 1, 0, Top level record
>
>  
>
> I'm wondering if anyone can help me work out how to achieve this?
>
>  
>
> Many thanks in advance!
>
>  
>
> Much warmth,
>
>  
>
> Murray
>
>  <http://www.planetthoughtful.org/> http://www.planetthoughtful.org
>
> Building a thoughtful planet,
>
> One quirky comment at a time.
>
>  

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