File: ccelko.php

Recommend this page to a friend!
  Classes of Filippo Toso  >  Joe Celko Nested Sets  >  ccelko.php  >  Download  
File: ccelko.php
Role: Class source
Content type: text/plain
Description: CCelkoNastedSet class file
Class: Joe Celko Nested Sets
Manage tree database structure with Celko approach
Author: By
Last change: Small changes in credits
Date: 16 years ago
Size: 22,854 bytes
 

 

Contents

Class file image Download
<?php 
/*
	CCelkoNastedSet class 

	Thanks to Kirill Hryapin kx@chl.ru for finding and solving bugs into the MoveNode () method.

	Members
	$TableName => Table name that contains nasted sets 
	$FieldID => Field name for table ID
	$FieldIDParent => Field name for table IDParent
	$FieldLeft => Field name for table nasted set left field 
	$FieldRight => Field name for table nasted set right field  
    $FieldDiffer => Field name used to manage more than one type of nasted set in the same table
	$FieldLevel => Field name for table nasted set level field  (0 = root node)
	$FieldOrder => Field name for table nasted set order field   
	$FieldIgnore => Field name for tablr nested set ignore field 
	
	$TransactionTable => Name for table used to manage transactions

	$MyLink => MySQL database link resource

	Methods 
	SelectSubNodes () => Returns all the sub node of IDNode fo Level number of level.
	SelectPath () => Returns the path from the IDNode to the root node.
	MoveNode () => Method used to move the node IDNode to IDParent.
	AddRootNode () => Method used to add the root node for a nested set
	AddNode () => Method used to add a node to IDParent. Return the new IDNode.
	DeleteNode () => Method used to delete the node identified by IDNode and all his children.
	ClearNodes () => Method used to clear the nasted set table

	BeginTransaction () => Method that start the transaction. Returns true or false.
	EndTransaction () => Method that stop the transaction.
	IsInTransaction () => Method to check the transaction state. Returns true or false.

	SQL STRUCTURE
	The structure of tblCelkoTransTable must me mainteined, the structure of tblNastedSets could be modified, 
	you can add columns but you must maintain the NSFields needed for celko's nasted sets.
		
	CREATE TABLE tblCelkoTransTable (
	  IDTransaction INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
	  TableName TINYTEXT NULL,
	  Differ TINYTEXT NULL,
	  InTransaction BIT NULL,
	  TStamp TIMESTAMP NULL,
	  PRIMARY KEY(IDTransaction)
	);
	
	CREATE TABLE tblNastedSets (
	  IDNode INTEGER UNSIGNED NOT NULL AUTO_INCREMENT,
	  IDParent INTEGER UNSIGNED NULL DEFAULT '0',
	  NSLeft INTEGER UNSIGNED NULL DEFAULT '0',
	  NSRight INTEGER UNSIGNED NULL DEFAULT '0',
	  NSLevel INTEGER UNSIGNED NULL DEFAULT '0',
	  NSOrder INTEGER UNSIGNED NULL DEFAULT '1',
	  NSDiffer TINYTEXT NULL,
	  NSIgnore INTEGER UNSIGNED NULL DEFAULT '0',
	  PRIMARY KEY(IDNode)
	);

*/

class CCelkoNastedSet { 

   var $TableName; 
   var $FieldID; 
   var $FieldIDParent; 
   var $FieldLeft; 
   var $FieldRight; 
   var $FieldDiffer;
   var $FieldLevel; 
   var $FieldOrder; 
   var $FieldIgnore; 
   
   var $TransactionTable; 
   var $_IsInTransaction; 
   var $_TransactionTStamp; 

   var $MyLink; 

	function CCelkoNastedSet () 
	{ 
	   $this->TableName = "tblCelkoTree";  
	   $this->FieldID = "IDNode"; 
	   $this->FieldIDParent = "IDParent"; 
	   $this->FieldLeft = "NSLeft"; 
	   $this->FieldRight = "NSRight"; 
	   $this->FieldDiffer = "NSDiffer";
	   $this->FieldLevel = "NSLevel";  
	   $this->FieldOrder = "NSOrder"; 
	   $this->FieldIgnore = "NSIgnore"; 
	
	   $this->TransactionTable = "tblCelkoTransTable";  
	   $this->_IsInTransaction = false;
	   $this->_TransactionTStamp = 0;
	
	   $this->MyLink = null;  
	} 

	// Begin private functions //
	function _safe_set (&$var_true, $var_false = "")
	{
		if (!isset ($var_true)) 
		{ $var_true = $var_false; }
	}

	function _safe_query ($query, $link)
	{
		if (empty($query)) { return false; }
		$result = mysql_query ($query, $link) or die("Error executing query: $query");
		return $result;
	}
	// End private functions //

	// Begin transaction functions //
	function InitializeTransaction ($Differ = "")
	{
		$sql_verify = "SELECT * FROM " . $this->TransactionTable .
					  " WHERE TableName = '" . $this->TableName . "' " .
					  " AND Differ = '" . $Differ . "'";
		$rs_verify = $this->_safe_query ($sql_verify, $this->MyLink);
		
		if (($rs_verify) && (mysql_num_rows ($rs_verify) == 0))
		{
			mysql_free_result ($rs_verify);
			
	   		$sql_insert = "INSERT INTO " . $this->TransactionTable . 
						  " (TableName, Differ, InTransaction) " .
						  " VALUES ('" . $this->TableName . "', '" . $Differ . "', 0)";
			$this->_safe_query ($sql_insert, $this->MyLink);
			
			return true;
		}
		else
		{ return false; }
	}

	function BeginTransaction ($Differ = "")
	{
		$TStamp = date ("YmdHis");

		$sql_update = "UPDATE " . $this->TransactionTable . 
					  " SET TStamp = " . $TStamp . ", " .
					  " InTransaction = 1 " .
					  " WHERE InTransaction = 0 " .
					  " AND TableName = '" . $this->TableName . "' " .
					  " AND Differ = '" . $Differ . "'";
		$this->_safe_query ($sql_update, $this->MyLink);
		
		$sql_verify = "SELECT * FROM " . $this->TransactionTable .
					  " WHERE TableName = '" . $this->TableName . "' " .
					  " AND InTransaction = 1 " .
					  " AND TStamp = " . $TStamp . 
					  " AND Differ = '" . $Differ . "'";
		$rs_verify = $this->_safe_query ($sql_verify, $this->MyLink);

		if (($rs_verify) && (mysql_num_rows ($rs_verify) == 1))
		{
			mysql_free_result ($rs_verify);
			$this->_IsInTransaction = true;
			$this->_TransactionTStamp = $TStamp;
			return true;
		}
		else
		{ 
			$this->_IsInTransaction = false;
			$this->_TransactionTStamp = 0;
			return false; 
		}
	}
	
	function EndTransaction ($Differ = "")
	{
		$sql_update = "UPDATE " . $this->TransactionTable . 
					  " SET InTransaction = 0 " .
					  " WHERE TableName = '" . $this->TableName . "' " .
					  " AND TStamp = " . $this->_TransactionTStamp . 
					  " AND Differ = '" . $Differ . "'";
		$this->_safe_query ($sql_update, $this->MyLink);
		$this->_IsInTransaction = false;
	}

	function IsInTransaction ()
	{ return $this->_IsInTransaction; }
	// End transaction  functions //
	
	// Begin nasted set functions //
	function ClearNodes ($Differ = "") 
	{
		$sql_delete = "DELETE FROM " . $this->TableName . " WHERE " . $this->FieldDiffer . " = '" . $Differ . "'";
		$this->_safe_query ($sql_delete, $this->MyLink);
	}

	function DeleteNode ($IDNode = -1, $Differ = "") 
	{
		if (!$this->_IsInTransaction)
		{ return false; }
		
		$sql_select = "SELECT * FROM " . $this->TableName . " WHERE " . $this->FieldID . " = " . $IDNode . " AND " . $this->FieldDiffer . " = '" . $Differ . "'"; 
		$rs_select = $this->_safe_query ($sql_select, $this->MyLink);
		if (($rs_select) && ($row_select = mysql_fetch_assoc ($rs_select)))
		{
			$this->_safe_set ($row_select[$this->FieldID], -1);
			$this->_safe_set ($row_select[$this->FieldLeft], -1);
			$this->_safe_set ($row_select[$this->FieldRight], -1);
			$delete_offset = $row_select[$this->FieldRight] - $row_select[$this->FieldLeft];

			// Delete sub nodes
			$sql_delete = "DELETE FROM " . $this->TableName . 
						  " WHERE " . $this->FieldLeft . " >= " . $row_select[$this->FieldLeft] . 
						  " AND " . $this->FieldLeft . " <= " . $row_select[$this->FieldRight] .
						  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
			$this->_safe_query ($sql_delete, $this->MyLink);

			// Update FieldLeft 
			$sql_update = "UPDATE " . $this->TableName . 
						  " SET " . $this->FieldLeft . " = " . $this->FieldLeft . " - " .  ($delete_offset + 1) .
						  " WHERE " . $this->FieldLeft . " > " . $row_select[$this->FieldRight] .
						  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
			$this->_safe_query ($sql_update, $this->MyLink);

			// Update FieldRight 
			$sql_update = "UPDATE " . $this->TableName . 
						  " SET " . $this->FieldRight . " = " . $this->FieldRight . " - " .  ($delete_offset + 1) .
						  " WHERE " . $this->FieldRight . " > " . $row_select[$this->FieldRight] . 
						  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
			$this->_safe_query ($sql_update, $this->MyLink);
		
			mysql_free_result ($rs_select);			

			return true;
		}
		else
		{ return false; }
	}

	function AddRootNode ($Differ = "") 
	{
		if (!$this->_IsInTransaction)
		{ return false; }

		$sql_insert = "INSERT INTO " . $this->TableName . 
					  " (" . $this->FieldIDParent . ", " . $this->FieldLeft . ", " . $this->FieldRight . 
					  ", " . $this->FieldLevel . ", " . $this->FieldOrder . ", " . $this->FieldDiffer . ") " .
					  " VALUES (0, 1, 2, 0, 1, '" . $Differ . "')";
		$this->_safe_query ($sql_insert, $this->MyLink);
		return mysql_insert_id ($this->MyLink);
	}

	function AddNode ($IDParent = -1, $Order = -1, $Differ = "") 
	{
		if (!$this->_IsInTransaction)
		{ return false; }

		$sql_select = "SELECT * FROM " . $this->TableName . " WHERE " . $this->FieldID . " = " . $IDParent . " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
		$rs_select = $this->_safe_query ($sql_select, $this->MyLink);
		if (($rs_select) && ($row_select = mysql_fetch_assoc ($rs_select)))
		{
			$this->_safe_set ($row_select[$this->FieldID], -1);
			$this->_safe_set ($row_select[$this->FieldLeft], -1);
			$this->_safe_set ($row_select[$this->FieldRight], -1);
			$this->_safe_set ($row_select[$this->FieldLevel], -1);
			
			$left = $row_select[$this->FieldLeft] + 1;
		
			// Update Order (set order = order +1 where order>$Order)
			if ($Order == -1)
			{
				$sql_order = "SELECT * FROM " . $this->TableName . 
							 " WHERE " . $this->FieldIDParent . " = " . $IDParent .
						  	 " AND " . $this->FieldDiffer . " = '" . $Differ . "'" .
							 " ORDER BY " . $this->FieldOrder . " DESC " .
							 " LIMIT 0,1";
				$rs_order = $this->_safe_query ($sql_order, $this->MyLink);
				if (($rs_order) && ($row_order = mysql_fetch_assoc ($rs_order)))
				{
					$this->_safe_set ($row_order[$this->FieldOrder], 0);
					$Order = $row_order[$this->FieldOrder] + 1;
					mysql_free_result ($rs_order);
				}
				else
				{ $Order = 1; }
			}

			$sql_update = "UPDATE " . $this->TableName . 
						  " SET " . $this->FieldOrder . " = " . $this->FieldOrder . " + 1" .
						  " WHERE " . $this->FieldIDParent . " = " . $IDParent .
						  " AND " . $this->FieldOrder . " >= " . $Order . 
						  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
			$this->_safe_query ($sql_update, $this->MyLink);
			
			$sql_order = "SELECT * FROM " . $this->TableName . 
						 " WHERE " . $this->FieldIDParent . " = " . $IDParent .
						 " AND " . $this->FieldOrder  . " <= " . $Order .
						 " AND " . $this->FieldDiffer . " = '" . $Differ . "'" .
						 " ORDER BY " . $this->FieldOrder . " DESC " .
						 " LIMIT 0,1";
			$rs_order = $this->_safe_query ($sql_order, $this->MyLink);
			if (($rs_order) && ($row_order = mysql_fetch_assoc ($rs_order)))
			{
				$this->_safe_set ($row_order[$this->FieldRight], -1);
				$left = $row_order[$this->FieldRight] + 1;
				mysql_free_result ($rs_order);
			}
			
			$right = $left + 1;
			
			// Update FieldLeft 
			$sql_update = "UPDATE " . $this->TableName . 
						  " SET " . $this->FieldLeft . " = " . $this->FieldLeft . " + 2" .
						  " WHERE " . $this->FieldLeft . " >= " . $left .
					  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
			$this->_safe_query ($sql_update, $this->MyLink);
			
			// Update FieldRight 
			$sql_update = "UPDATE " . $this->TableName . 
						  " SET " . $this->FieldRight . " = " . $this->FieldRight . " + 2" .
						  " WHERE " . $this->FieldRight . " >= " . $left .
					  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
			$this->_safe_query ($sql_update, $this->MyLink);

			// Insert
	   		$sql_insert = "INSERT INTO " . $this->TableName . 
						  " (" . $this->FieldIDParent . ", " . $this->FieldLeft . ", " . $this->FieldRight . 
						  ", " . $this->FieldLevel . ", " . $this->FieldOrder . ", " . $this->FieldDiffer . ") " .
						  " VALUES (" . $IDParent . ", " . $left . ", " . $right . 
						  ", " . ($row_select[$this->FieldLevel] + 1) . ", " . $Order . ", '" . $Differ . "')";
			$this->_safe_query ($sql_insert, $this->MyLink);

			mysql_free_result ($rs_select);

			return mysql_insert_id ($this->MyLink);
		}
		else
		{ return false; }
	}

	function MoveNode ($IDNode = -1, $IDParent = -1, $Order = -1, $Differ = "")
	{
		if (!$this->_IsInTransaction)
		{ return false; }

		$sql_select = "SELECT * FROM " . $this->TableName .
		              " WHERE " . $this->FieldID . " = " . $IDNode .
		              " AND " . $this->FieldDiffer . " = '" . $Differ . "'";

		$rs_select = $this->_safe_query ($sql_select, $this->MyLink);
		if (($rs_select) && ($row_select = mysql_fetch_assoc ($rs_select)))
		{
			$this->_safe_set ($row_select[$this->FieldID], -1);
			$this->_safe_set ($row_select[$this->FieldLeft], -1);
			$this->_safe_set ($row_select[$this->FieldRight], -1);
			$this->_safe_set ($row_select[$this->FieldLevel], -1);
			$delete_offset = $row_select[$this->FieldRight] - $row_select[$this->FieldLeft];


			$sql_select_parent = "SELECT * FROM " . $this->TableName .
			                     " WHERE " . $this->FieldID . " = " . $IDParent .
			                     " AND " . $this->FieldDiffer . " = '" . $Differ . "'";

			$rs_select_parent = $this->_safe_query ($sql_select_parent, $this->MyLink);
			if (($rs_select_parent) && ($row_select_parent = mysql_fetch_assoc ($rs_select_parent)))
			{
				$this->_safe_set ($row_select_parent[$this->FieldID], -1);
				$this->_safe_set ($row_select_parent[$this->FieldLeft], -1);
				$this->_safe_set ($row_select_parent[$this->FieldRight], -1);
				$this->_safe_set ($row_select_parent[$this->FieldLevel], -1);

				$left = $row_select_parent[$this->FieldLeft] + 1;

				//Set node tree as ignore
				$sql_ignore = "UPDATE " . $this->TableName .
							  " SET " . $this->FieldIgnore . " = 1" .
							  " WHERE " . $this->FieldLeft . " >= " . $row_select[$this->FieldLeft] .
							  " AND " . $this->FieldRight . " <= " . $row_select[$this->FieldRight] .
						  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				$this->_safe_query ($sql_ignore, $this->MyLink);

				// Update Order (set order = order +1 where order>$Order)
				if ($Order == -1)
				{
					$sql_order = "SELECT * FROM " . $this->TableName .
								 " WHERE " . $this->FieldIDParent . " = " . $IDParent .
								 " AND " . $this->FieldDiffer . " = '" . $Differ . "'" .
								 " ORDER BY " . $this->FieldOrder . " DESC " .
								 " LIMIT 0,1";
					$rs_order = $this->_safe_query ($sql_order, $this->MyLink);
					if (($rs_order) && ($row_order = mysql_fetch_assoc ($rs_order)))
					{
						$this->_safe_set ($row_order[$this->FieldOrder], 0);
						$Order = $row_order[$this->FieldOrder] + 1;
						mysql_free_result ($rs_order);
					}
					else
					{ $Order = 1; }
				}

				$sql_update = "UPDATE " . $this->TableName .
							  " SET " . $this->FieldOrder . " = " . $this->FieldOrder . " + 1" .
							  " WHERE " . $this->FieldIDParent . " = " . $IDParent .
							  " AND " . $this->FieldOrder . " >= " . $Order .
							  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				$this->_safe_query ($sql_update, $this->MyLink);

				$sql_order = "SELECT * FROM " . $this->TableName .
							 " WHERE " . $this->FieldIDParent . " = " . $IDParent .
							 " AND " . $this->FieldOrder  . " <= " . $Order .
							 " AND " . $this->FieldDiffer . " = '" . $Differ . "'" .
							 " ORDER BY " . $this->FieldOrder . " DESC " .
							 " LIMIT 0,1";
				$rs_order = $this->_safe_query ($sql_order, $this->MyLink);
				if (($rs_order) && ($row_order = mysql_fetch_assoc ($rs_order)))
				{
					$this->_safe_set ($row_order[$this->FieldRight], -1);
					$left = $row_order[$this->FieldRight] + 1;
					mysql_free_result ($rs_order);
				}

				$child_offset = $row_select[$this->FieldRight] - $row_select[$this->FieldLeft] + 1;

				// Update FieldLeft
				if ($left < $row_select[$this->FieldLeft]) // Move to left
				{
					$sql_update = "UPDATE " . $this->TableName .
								  " SET " . $this->FieldLeft . " = " . $this->FieldLeft . " + (" . $child_offset . ")" .
								  " WHERE " . $this->FieldLeft . " >= " . $left .
								  " AND " . $this->FieldLeft . " <= " . $row_select[$this->FieldLeft] .
								  " AND " . $this->FieldIgnore . " = 0" .
								  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				}
				else // Move to right
				{
					$sql_update = "UPDATE " . $this->TableName .
								  " SET " . $this->FieldLeft . " = " . $this->FieldLeft . " - " . $child_offset .
								  " WHERE " . $this->FieldLeft . " <= " . $left .
								  " AND " . $this->FieldLeft . " >= " . $row_select[$this->FieldLeft] .
								  " AND " . $this->FieldIgnore . " = 0" .
								  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				}
				$this->_safe_query ($sql_update, $this->MyLink);

				// Update FieldRight
				if ($left < $row_select[$this->FieldLeft]) // Move to left
				{
					$sql_update = "UPDATE " . $this->TableName .
								  " SET " . $this->FieldRight . " = " . $this->FieldRight . " + (" . $child_offset . ")" .
								  " WHERE " . $this->FieldRight . " >= " . $left .
								  " AND " . $this->FieldRight . " <= " . $row_select[$this->FieldRight] .
								  " AND " . $this->FieldIgnore . " = 0" .
								  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				}
				else // Move to right
				{
					$sql_update = "UPDATE " . $this->TableName .
								  " SET " . $this->FieldRight . " = " . $this->FieldRight . " - " . $child_offset .
								  " WHERE " . $this->FieldRight . " < " . $left .
								  " AND " . $this->FieldRight . " >= " . $row_select[$this->FieldRight] .
								  " AND " . $this->FieldIgnore . " = 0" .
								  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				}
				$this->_safe_query ($sql_update, $this->MyLink);

				$level_difference = $row_select_parent[$this->FieldLevel] - $row_select[$this->FieldLevel] + 1;
				$new_offset = $row_select[$this->FieldLeft] - $left;
                if ($left > $row_select[$this->FieldLeft]) // i.e. move to right
                { $new_offset += $child_offset; }

				//Update new tree left
				$sql_update = "UPDATE " . $this->TableName .
							  " SET " . $this->FieldLeft . " = " . $this->FieldLeft . " - (" . $new_offset . "), " .
							  $this->FieldRight . " = " . $this->FieldRight . " - (" . $new_offset . ")," .
							  "$this->FieldLevel = $this->FieldLevel + $level_difference" .
							  " WHERE " . $this->FieldLeft . " >= " . $row_select[$this->FieldLeft] .
							  " AND " . $this->FieldRight . " <= " . $row_select[$this->FieldRight] .
							  " AND " . $this->FieldIgnore . " = 1" .
						  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				$this->_safe_query ($sql_update, $this->MyLink);

				//Remove ignore statis from node tree
				$sql_ignore = "UPDATE " . $this->TableName .
							  " SET " . $this->FieldIgnore . " = 0" .
							  " WHERE " . $this->FieldLeft . " >= " . ($row_select[$this->FieldLeft] - $new_offset) .
							  " AND " . $this->FieldRight . " <= " . ($row_select[$this->FieldRight] - $new_offset) .
							  " AND " . $this->FieldIgnore . " = 1" .
						  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
				$this->_safe_query ($sql_ignore, $this->MyLink);

				//Update insert root field
				$sql_update = "UPDATE " . $this->TableName . " SET " . $this->FieldIDParent . " = " . $IDParent . ", " .
							  $this->FieldOrder . " = " . $Order . " WHERE " . $this->FieldID . " = " . $IDNode;
				$this->_safe_query ($sql_update, $this->MyLink);

				mysql_free_result ($rs_select_parent);
				return true;
			}
			else
			{ return false; }

			mysql_free_result ($rs_select);
			return true;
		}
		else
		{ return false; }
	}

	function SelectPath ($IDNode = -1, $Differ = "") 
	{
		if (!$this->_IsInTransaction)
		{ return false; }

		$sql_select = "SELECT * FROM " . $this->TableName . " WHERE " . $this->FieldID . " = " . $IDNode . " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
		$rs_select = $this->_safe_query ($sql_select, $this->MyLink);
		if (($rs_select) && ($row_select = mysql_fetch_assoc ($rs_select)))
		{
			$this->_safe_set ($row_select[$this->FieldID], -1);
			$this->_safe_set ($row_select[$this->FieldLeft], -1);
			$this->_safe_set ($row_select[$this->FieldRight], -1);
			$sql_result = "SELECT * FROM " . $this->TableName . 
						  " WHERE " . $this->FieldLeft . " <= " . $row_select[$this->FieldLeft] .
						  " AND " . $this->FieldRight . " >= " . $row_select[$this->FieldRight] . 
					  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'" . 
						  " ORDER BY " . $this->FieldLeft;
			mysql_free_result ($rs_select);
			return $this->_safe_query ($sql_result, $this->MyLink); // Remember to free result			  
		}
		else
		{ return false; }
	}

	function SelectSubNodes ($IDNode = -1, $Level = -1, $Differ = "") 
	{
		if (!$this->_IsInTransaction)
		{ return false; }

		$sql_select = "SELECT * FROM " . $this->TableName . " WHERE " . $this->FieldID . " = " . $IDNode . " AND " . $this->FieldDiffer . " = '" . $Differ . "'";
		$rs_select = $this->_safe_query ($sql_select, $this->MyLink);
		if (($rs_select) && ($row_select = mysql_fetch_assoc ($rs_select)))
		{
			$this->_safe_set ($row_select[$this->FieldID], -1);
			$this->_safe_set ($row_select[$this->FieldLeft], -1);
			$this->_safe_set ($row_select[$this->FieldRight], -1);
			$this->_safe_set ($row_select[$this->FieldLevel], -1);
			if ($Level == -1) // All child nodes
			{
				$sql_result = "SELECT * FROM " . $this->TableName . 
							  " WHERE " . $this->FieldLeft . " >= " . $row_select[$this->FieldLeft] .
							  " AND " . $this->FieldRight . " <= " . $row_select[$this->FieldRight] . 
						  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'" .
							  " ORDER BY " . $this->FieldLevel . "," . $this->FieldOrder;
			}
			else // Only $Level child nodes
			{
				$sql_result = "SELECT * FROM " . $this->TableName . 
							  " WHERE " . $this->FieldLeft . " >= " . $row_select[$this->FieldLeft] .
							  " AND " . $this->FieldRight . " <= " . $row_select[$this->FieldRight] . 
							  " AND " . $this->FieldLevel . " <= " . ($Level + $row_select[$this->FieldLevel]) . 
						  	  " AND " . $this->FieldDiffer . " = '" . $Differ . "'" .
							  " ORDER BY " . $this->FieldLevel . "," . $this->FieldOrder;
			}
			mysql_free_result ($rs_select);
			return $this->_safe_query ($sql_result, $this->MyLink); // Remember to free result			  
		}
		else
		{ return false; }
	}
	// End nasted set functions //
} 

?>

For more information send a message to info at phpclasses dot org.